It shouldnt actup at all. If it acts up then I think you should scan for any viruses, seriously. It sounds to me like it got corrupt.

If you dont have any anti virus software, here is a trusted site where you can get a free one:

http://www.snapfiles.com/freeware/security/fwvirus.html

sometimes you can unknowningly pickup a virus or a trojan while downloading from Gnutella. and if thats not it, then someone will be by to offer some more advice. or, maybe you need to do a fresh install if windows cant find the .exe?