Answer
This question was answered on April 17, 2006.
Much of the information contained herein may have changed since posting.
It's hard to say if the virus is causing your system to freeze while running an anti virus program but that isn't entirely impossible either. The best suggestion I can make is to start your computer in safe mode and try running your anti spyware in safe mode. Another thing you can do to find a virus is to click cntrl+alt+delete and look at the processes running. You may have to go through each one and type the name of the program into a Google search. In most instances, there's some website out there that will be able to tell you what the program is and what it does. If there's a virus in your computer, you'll find it in the processes that are running on your computer. Be prepared to have to manually delete the virus especially if it won't let you run your anti virus.