Originally Posted by undergrd

I scan my pc with AVG free anti virus but nothing was found. Could it be related to any pc settings?

Normally, you open your c drive with explorer by default (with a shell cmd handled by OS). it's not likely that you have done any change to System on this critical area (It's related to several registry entries). So my guess is, your system is either damaged by a virus or by someone else who played a trick on u.

If the virus merely modified your explorer registry entries, virtually 90% AV software couldn't detect such virus. You'd better do some system restore. At the best, you can find someone expert at this problem to fix it for you.

Another possibility is (worse) : the virus also placed some malicious code into the hidden file. When you double click your drive icon, your system then starts to seek an appropriate program to open the hidden file generated by the virus. If the system fails to find one, it will give you a prompt dialog asking you to manually choose one. In this case, the virus is probably already cleared, but left some scum in your system which is not recognized as a threat. The solution is also to run restore or find someone with adequate knowledge.

hope this helps

DeXtmL