All sounds like some nefarious dealings going on. As far as browser hijacking is concerned, usually it doesn't prohibit you from browsing the internet; it usually pops up many additional browsers with some junk search sites and from there they each start travelling the net. But not limited to that.
As far as not being able to access Site B while you can access Site A has many culprits. If I was to troubleshoot it, I'd make sure that the connection you have, is actually there. Obviously it's truely there sometimes, you all post messages here.
But when you loose it again. Go to a command window (start | run | cmd.exe ) and run the program ipconfig.exe
(This is for Win 2000 or XP, 9x & Me is a different program that I can't remember what it is. I will look into it if someone needs me to)
This will give you details on your connection to the internet.
Basically what you are looking for is a valid IP address. The only really way I can explain a real ip address is that it WON'T look like, 192.168.xxx.xxx and it wont look like 127.0.0.xxx. Where xxx will be some number (0-255)
If the number DOES look like those, you can run ipconfig /release AND then run ipconfig /renew .
If that doesn;t work (numbers reappear or it still doesnt access the site(s)) fully restart the computer, that is shut down AND turn off power. Then reboot and reconnect to internet.
I really doubt that this is any of your problems (because you seem to be able to access this site okay) but I'm going through the long desc, just in case this is an intermitten problem.
Next question I'd have if it still gives you issues, is are you running a wireless network that includes your internet connection? (I.e. Cable or DSL internet AND a wireless network)
If so, you may have a problem with your wireless hardware 'hickupping' . Nothing serious, it happens all the time to me and I know why, just haven't invested the effort to correct it. What this may be is a story. Computers (especially XP) will hibernate, sleep, and 'power' down unneed pieces of hardware to save power and usage. This happens when you leave the computer on and walk away for a period of time. I have found that my computer, XP Pro, powers down the network controller (gives me access to the wireless network) during this period of time. When I come back, the computer 'wakes' the unused hardware (monitor, etc), but it seems the network controller has problems waking up. To fix this, I reboot the computer. pain in the but, just haven't figured out what is wrong here to correct it .
So if you are on a wireless network AND these problems of not being able to get to the sites happens after you return to the computer, after it's powered down, this could be your problem, and to fix it, reboot.
If that still isn't your problem next step is the browser and the 'url' being used. Usually things are cool here but I thought I'd mention it because Carlton typed symantec.com like that and not http://www.symantec.com/ .
The internet is a HUGE immense place. Not only is it big, many different 'languages' (thats the http or ftp or gopher and more) are being spoken between the computers. Also, for each address (symantec.com, msn.com, luthiersforum.com, etc), there is many different 'sub-addresses' (generically www, ftp, w3, and MANY more) so as you can imagine the possibilities are endless as to what a web site can provide, and thus what a user can access.
Browsers give a user a program to access sites with sub sites using a language. But the browser needs to know what language to use, you tell it by typing http. It also needs to know the sub-site (www, ftp, etc [really it's a unique 'computer' on the symantec.com domain]).
Now if you just type symantec.com in the address bar of your browser, it should be able to figure out it's http://www.symantec.com/ by itself. the browser will do this by querying symantec.com by going through the most likely suspect (http & www). If it doesn't get a reply back from the site in a reasonable amount of time (for WHATEVER reason and we'll get to that) using http & www the browser doesn't know what to do, so you get the page can't be displayed or site not found, etc. you get an error.
So, at this point, just to make sure, type out to full URL (universal resouce locator) of http://www.symantec.com/ and see what happens.
If, at this point you STILL get the errors / problems. Then I would guess that it's due to dropping packets between you and the site. So we need to ping it to see, in the command window type:
ping www.symantec.com /n 100
This will ping, send packets of information to symantec and symantec will return it once received. If a packet is dropped on either leg of the trip, it will say 'Request Time Out' for that particular ping request, (we are actually sending 100 in this case)
So if it's 'request time out' a lot (more than not) then hit the key combination CTRL+C to stop the program.
If there aren't any dropped packets, then it's something else. But if there are packets dropped, we need to trace route it now. Trace routing pings every computer along the path between you (only you) and www.symantec.com. There will be alot and each one is called a hop. (actually most AREN:T computers here, they are switches and router, but they are computers in their own rights)
After the ping completed above it will display the results. Key here is the Lost amount/percentage. If there are any, the internet service provider you have is dropping the ball. BUT what we are looking for really is a signigant percentage, more than 2% will cause headaches (sometimes pages won't display EVERY picture, or simple pages take A LONG TIME to load.) Anything over 4% you will see this with MANY sites, more than 10% very few sites will work correctly. More than 20% and NOTHING works.
Trace routing will tell you where along the internet path the problem lies.
Type this in the command window.
tracert www.symantec.com -d -h 255
How this works is tracert actually pings the site, but it tells ping to only allow 1 hop for the first, 2 hops for the second 3 for the third and so on till it traverses every hop between you and symantec. By doing this it determines the computer/router address at that particular hop.
Once it determines the computer there, it pings that address with 3 pings. Goes on to the next, 3 pings, next 3 pings and so on.
If the computer/router isnt responding at that hop or for a ping, it will display a *. Don't worry if you see a star for 1 of the 3 pings at an address. It's quite common due to the settings tracert uses. Don't even worry about 3 *'s for a single address, this might mean the computer / router was set up to NOT respond to pings. What you do worry about is at some point EVERY address will show 3 *'s.
And the first one is the culprit. Write down the address of the computer (you can scroll the window if it falls off the top) and call your internet service provider help line and tell them about your computer problems and then tell them you got trace route and ping data showing the problem.
When you are talking to them, make sure they understand your displeasure with their service. I demand reimbursement for the month when this happens. Sometimes I get it, sometimes not. Your success may vary. But be sure to understand that you are paying a service that you expect to be able to use. And when they say, 'this isn't in our control, we can't be held responsible.' that is bunk. You pay a premimum price, so should they (an internet provider themselves pay for internet access through other providers. and they themselves like to change it week to week, causing problems for you a lot of times [ISP is now a commodity]) You get what you pay for.
Okay, if this wasn't your problem, then it's mostly virus, spyware, etc. Go download AdAware http://www.lavasoft.de/. This is an AWESOME AWESOME AWSOME piece of software.
Like anti-virus AdAware is anti-spyware, and it's FREE!
This has either taken care of all my spyware problems or pointed them out to me. (so can be removed, except manually **see below for the worse type of spyware**
With AdAware it should take care of your problems. If it doesn't you need a computer technician to look at your computer. At this point, it sounds like the computer just isn't hanging on anymore due to too many crashes, power outages, bad power downs, etc and needs to be wiped and all software reinstalled. Sorry, but that sort of thing doesn't fit well on a BBS or over the phone, really needs a tech to do it. If you are near the akron area, i'd be happy to help myself. Been doing this for many years, probably more than most luthier's here have been making fine saw dust.

Well maybe, not... But it's been a LONG time.
Okay, for the worst spyware I've seen. Background, I have a movie called 'Downfall' that is about the last 12? days of the Third Riech. Same people that made Das Boot made this film. I absolutely love this film because it portrays Hitler as some OTHER than stupid. He's still an Egotistical maniac, but not stupid.
At any rate, I wanted to back this up onto my computer and another DVD. Since I don't do this all the time, I had to start from scratch, obtaining software to retrieve the DVD info, stuff to organize it, stuff and stuff to burn it to DVD.
Well I got every thing together and started the extremely LONG process of copying the DVD. Midway through I wanted to view the files to make sure they were okay and not currupted. Dang it, it's a DivX format file. So off to DivX to get the free codec to view DivX video files.
I install it, continue on and it seems okay. Except computer seem 'funky' to say the least. I'm not even browsing the internet and every fiew minutes I get browsers popping up all over the place. (Browser hijacking

)
Also, the screen flickers. (Hidden spyware app reporting your doings on your computer)
And sometimes the computer is DOG slow. (Something using your processor to do something, who knows the reason it is.)
The spyware browser hijacking portion would also take you to sites that actually had viruses on them. I think I ended up with 20 or so viruses in the end even WITH symantec running.
So looking at the running processes, there were a few suspicious processes. I'd kill them and they'd magically reappear (regenerating spyware). eeee so what, just means someother process is watching the first and recreates the process once it's ended. But I couldn't find the source, until I found out it's a Windows Service now. (A service is a serious operating system component) Now this has REALLY pissed me off.
Search the internet, go to symantec BINGO they know what it is; so I print the instructions and description out. Go read a while.
Man this spyware (not virus, because I asked for it with the freeware DivX codec installation) was a real piece of work.
It had SO many things watching itself and was able to randomize and regenerate. This is what made it so hard to remove. AdAware and other spyware removal tools couldn't take care of these because of the random nature. The instructions were something like, 'in this directory look for a file that may have a file name with random numbers and letters with win32 at the beginning or end and may be hidden.'
And you had to registry edit, delete files, go to the source site and download their uninstaller and still go through the hoops. All of this had to be taken in extreme EXACT order or else you had to start over.
I forget the spyware name , something like 'computer associates'. Each of the viruses was either a panda or trojan variant.
Really pisses me off sometimes.
Well that is enough rambling for me. Been at work for quite a while now and haven't gotten ANYTHING done...
Let me know what's going on and I'll try and do what I can.
-Rick