I have exactly the same problem. Yesterday I found a worm on my PC, the one that makes the taskbar and start menu and everything else disappear from my desktop. Apparently it is called Trojan.ByteVerify , according to my Norton Antivirus Software.

Well, I thought I had removed it by following the instructions on Symantec's website, and it worked fine for a while ( a few hourse) and then........

...then funny things started happening. Here are three very strange symptoms that I have noticed:

1. Every time Windows is started (or restarted), the folder C:\Windows\system32 opens

2. Everything, and I mean every single action (opening folders, clicking buttons) is very VERY slow

3. Internet Explorer has stopped working altogether (shows page not found) even though my internet is connected fine. (I know coz I am writing this post from my PC using Netscape Navigator).