Please no need for double posting.
Your other post is still there waiting for someone to reply, not many people are online at this hour anyway.
What does your event viewer have to show? That might be very useful checking it. Also have you tried a virus or trojan scan, maybe even run ad aware or spybot for any bad programs?
If you don't have much info in the event viewer then this will make it much harder to isolate the problem, also have you run windows update recently?
If nothing in the even viewer than you may have to consider a reinstall or maybe a repair, however the repair doesn't always catch everything, your best option would be to reinstall of nothing else is showing up as a problem.
Maybe back up your stuff and sit down with your colleague and make sure he doesn't do it again
Just back up all your important stuff and maybe do a reinstall.
However if incase your event viewer does hold some useful information go check
http://support.microsoft.com/default.aspx
the knowledge database for any information to see if it comes up with any fix for your situation or if it shows what network services you could try reinstalling the networking services, that have corrupted.
be sure to back up any files that you may need like config files or other files like with the ftp or http.
good luck