Malware problem

This past weekend, my PC was attacked by what I thought was ad-ware. My desktop background turned blue. I had the following security programs running:

- PC Tools AntiVirus Free Edition
- PC Tools Spyware Doctor Starter Edition 5.5

Both were up to date. I ran both of these programs butthey did nothing. I also ran HijackThis, but it didnt help either. In normal mode, the PC would either freeze or I didnt get a response when clicking on desktop icons, even if the PC itelf hadnt froze. When I was able to get some programs to work, every time I clicked on the SBC! Yahoo ico on my desktop, the internet window would open and run for a few seconds, but then I would get the following message:

"YCommon Exe Module has encountered a problem and needs to close. We are sorry for your inconvenience."

I eventually started the computer in Safe Mode with Networking and installed PC Tools ThreatFire Free Edition. However in normal mode it would either freeze in the middle of scanning my computer, not respond when I tried to open it, or I would get one of these messages when trying to open it:

"PCTools Security Service has encountered a problem and needs to close. We are sorry for the inconvenience."

or

"drwtsn32.exe - Application Error
The application failed to initialize properly (0xc0000142). Click on OK to terminate the application."

I eventually installed Malwarebytes' Anti-Malware 1.12 (trial version) and was able to run it in Safe Mode and then I replace PC Tools anti-virus with AVG Anti-Virus Free Edition 8.0.1 ans was able to run it in normal mode. So far, nothing has changed. The only way I can do anything on my computer is in Safe Mode with Networking but many malware-removal programs will not work in it. What else can I do?