Virus?

I've been having this problem for almost a week and I've put many hours into trying to fix it. I've been browsing through forums and trying everything that usually helps me out but nothing is working. The problem started after opening an infected file. My Ad-Watch began showing registry modifications and I rebooted and began trying to kill it with Ad-Aware, ect. It appeared to be caused by MediaAccess but continued after I deleted the files. I've tried the spy-ware and anit-virus programs your site suggests but none have resolved the problem fully. At this point Windows will start and Ad-Watch will occasionally show a registry mod for a value
[KavSvc] Windows/System32/rvmvlv.exe
I have removed this file and have removed it several times from the registry. I have not noticed any suspicious processes although svchost is often represented 2 or 3 times. The big problem is that none of my devices will work. My Device Manager will open, but it will not show any of my devices. Errors occur whenever I try to open software that uses a device. I tried reinstalling Windows today but was stopped by a message that said it could not find a hard drive on my machine. Thanks for the help.