My computer still is giving me problems.?

I had several good answers recently and tried some of them. I had already used Spyware and Adaware and tried to scan my hard drives and defrag. I am stopped from scanning C because it says something in Windows is running, and it won't defrag either. I downloaded Avast, and that worked great in that it found 2 Trojan Horses and 2 Worms. But I still can't download ErrorDoctor or upgrade Internet Explorer, and now every few minutes a Window box pops up saying the program has performed illegally. It has HPOSM in the top left corner of the box, but when I click OK on it, it doesn't shut me down like the usual illegal message box does. What is causing that, and why can't I download anything else, as the computer is still very, very slow. I also have a web page, and was told by my server that I should be using Internet Explorer 6. Since I haven't upgraded since 2003, I'm sure I don't have it. HELP!!

My computer still is giving me problems.?moto guzzi

I agree with the previous poster. You may want to try to run the scans in Safe Mode. Now since some of my suggestions may require you to access the internet, I suggest you go into Safe Mode with Networking. Then do the following.

A clean computer is key to a faster computer. Run the 3 scans below.

Run a virus scan weekly.

Update and run your Anti-Virus program. Don't have one? You can run a free online scan from CA.