gah... spyware is taking over... help!

Recently, I've been getting a lot of ads and pop-ups and my computer has been acting up. I've been getting this trojan virus that comes with an error message from AOL Instant Messenger. The error message reads something like "in order to access the AIM hyperlink, you must first sign on," and it will take you to the sign on window. The error message pops up all by itself (and will do so repeatedly, error messages piling up on top of each other), usually without me even starting AIM! The trojan that seems to result from this is easily caught, quarantined, and deleted with NAV, but the problem persists and it keeps coming back. Also, my favorite keyboard combination of CTRL+ALT+Delete doesn't work anymore, as the list of applications will pop up and disappear within seconds without any reason. Thus, I cannot access and shut down the more harmful applications that have found their way onto my computer manually.

So, I downloaded Spybot S&D, to complement the Adaware program I already had. Spybot scans and catches the harmful ad and spy programs excellently, but whenever i go to clear the programs from my computer, Spybot freezes in the middle of it, forcing me to close it down.

I have tried a system restore, but to no avail...

This is a vicious cycle here people... please help me end it! Thanks!