Internet Explorer lauches itself

I originally posted this in the general topic area, but was told it might be better to post it here. Since I’m pretty new to the forum (I have posted something once before, and found everyone to be very helpful), I didn’t know how to move it, so I’m posting it here, with a little more info.

For a while now, if I try to check out something in Control Panel or My Computer, or, once or twice even the search files area, Internet Explorer will suddenly launch, and bring up some page trying to advertise the latest anti spyware, or that I should scan my computer for spyware or virus’s. Usually I’m able to close the box when it opens up, so I’m not sure, exactly what it said the last time it did that.

I’m using the latest version of Avasts free anti virus, and have done a full scan and it has found nothing. (Although, before the Control Panel problem, I did a scan, and found 7 virus’s, which I sent to the chest, then deleted.). I also use SpyBot Search and Destroy, and it has also found nothing.

I’m using Windows 2000, and recently had to uninstall the free Comodo firewall because I was running into problems with it not starting. So, I’ll have to reinstall that, or find another firewall later.

My computer is old, and needs to be upgraded, as there is very little space left on it. So, downloading new programs may not be an option at the moment.

After running into problems with malware or adware in the past, I was advised to switch to Mozilla Firefox, which I now use instead of Explorer.

If anyone can offer help in this matter, it will be very much appreciated. Sorry to post this question more than once. Thanks!.

Did you follow my suggestions?
http://forum.avast.com/index.php?topic=34957.msg293495#msg293495
Maybe you can skip the installation of new programs but, really, they will help on troubleshooting.

RogueRemover is a utility that can remove various rogue antispyware, antivirus and hard drive cleaning utilities. Rogue applications are applications that rather than remove spyware, provide false positives, distribute malware or spyware, advertise, or provide useless uninstallers. The main point is that rogue applications are useless and eat up system resources.
Check http://www.malwarebytes.org/rogueremover.php