>>
>>This happened with this computer before.
>>
>>May be I need to re-start PC more often, I usually just lock computer when I go home...
>
>If it is an XP machine it wouldn't hurt to restart daily although XP is a pretty rock solid OS.
>
>If it is a STABLE Vista installation (I haven't worked with one that wasn't but I know some people have serious issues) then I wouldn't worry about a restart unless you are having really serious issues and can't find any other culprit.
>
>BTW I only use IE7 and do not have any other browser installed - that is why I'm wondering about FireFox and IE not playing well together..

This one a Windows XP. It got crushed pretty badly before, but our network guys re-built it in few days.

I'm testing ASP.NET application in FireFox, but as a browser I prefer IE7, though I think it's slower than FireFox...