Win XP SP2 with MS Anti Spyware installed, typical MS Apps installed and Adobe Apps.

Whenever I log on my Win XP, when i click my username then I input my passwrod a Dialog box will appear no Dialog box title and no text at all it only has YES and NO button with and X-icon (so i guess it was an error). Whatever button I clicked (YES/NO) it always returned me to the loggon screen and so on and so fort.

My friend told me it has something to do with registry entry shell=explorer.exe andsomefilethatwasnotknown.

I can enter into safe mode, i also tried system restore but no luck.

PLease help! Is this a virus or Windows Error!

Thanks!