Having problems, can't find the cause

I have been having problems with my computer since May 9, 2009. It is impossible to use the command prompt, run command, and the internet. I cannot restore due to problems with a nonexistant drive (F:). I've already run scans using ad-aware, nod32 antivirus, and various programs searching the registry. I really need some other options now.

What Windows are you on and have you tried the free version AVG 8.5? Also try Malwarebytes Anti-Malware and Hi-Jack This, but Hi-Jack This is for advance users only.

Try to also get the 30 day trial of System Mechanics, as it got some really good system tools to fix Windows. What do you mean you can't restore due to problems with a nonexistant drive? What make is the PC e.g. HP, Dell etc. and did you get a Windows disk with the machine?

I think I've found the cause. It was due to the deletion, instead of uninstallation, of a large amount of old files. Games I no longer play, applications I don't use, etc; This probably caused problems due to references in the registry.

Lets us know, how you get on.