I hope that someone can help me with this. We have a computer where we can't get any of the installed browsers to work: IE, Firefox, Chrome.

Background
My niece just came to live with us and brought her desktop computer with her (Windows XP Home). She claims that it was working fine at home and it seems to be working fine here. However, the web browsers don't work. This problem happens every time we try to launch a browser.

What Happens When Launching a Browser
After launching IE (version 8), the browser window opens and it says it's connecting. After sitting there for a few seconds, we get the pop-up window saying that they are sorry, but IE is having a problem and needs to close. After dismissing the message, the window stays open. If you try to close it, you get a separate "Sorry" message about closing an unresponsive program.

After attempting to launch Firefox (version 3.5 and the brower my niece normally uses), you just get a pop-up window apologizing that Firefox has to crash now and giving you options to either attempt to restart or quit. Restarting just gives you the same pop-up again. Quitting closes the window nicely.

With Chrome, it seems to go to la-la land when trying to open the default page (www.google.com). After waiting several minutes, I interrupted it's thoughts and tried to go to other pages and just got a message that the site was either unavailable or permanently moved.

Troubleshooting Attempts
I tried doing some research on this problem on the Internet and didn't come up with anything that seemed to match our problem. One discussion thread mentioned trying to launch a browser in Safe Mode. I tried this with mixed results. IE and Chrome work OK, but Firefox crashes the same way. I suggested to my niece that she just run everything in Safe Mode. She didn't think that was very funny.

When my niece's computer arrived, it just had IE and Firefox installed. I downloaded Chrome using IE while in Safe Mode hoping that Chrome might work after booting normally. Unfortunately, it did not.

I tried running Kaspersky anti-virus while in safe mode to see if there were any nasties hiding. This came back clean except for a couple of files that were detected with Weatherbug ad-ware and I'm certain that's not the problem.

I ran HijackThis and looked through the log (see attachment if you're interested) and nothing there really popped out to me, but I'm certainly not an expert.

This computer is attached to a home network along with four other computers that are not having this problem at all. I have tried pinging computers both on our home network as well as external sites. This works just fine. You can even send the crash reports to Microsoft and Mozilla that their browsers crashed. And I mentioned earlier that IE and Chrome work in Safe Mode.

Well, that's about all I know. If anyone can help me figure this out I would really appreciate it.

OK. I worked on it late last night trying to figure it out. In thinking about it, it was clear to me that either I had multiple problems (for each of the browsers), or that there was something that all had in common. That includes looking at the event logs.

What ended up fixing the problem was uninstalling two programs: AVG Antivirus and Adaware. I'm not sure which one of these was causing problems or if it was the two of them combined. I had just noticed that this computer had a whole bunch of antivirus and malware products installed and thought that it didn't need all of them so I decided to start hacking away at the pile to see if it made a difference. It turned out that it did.