Do have enough time to run hijackthis before it freezes? (installing it and running it should take no more than a minute or so.)

instructions here...

http://discussions.virtualdr.com/sho...d.php?t=167915


You could save some time by downloading it on another computer and burning it to a cd to transfer over to the infected one.

If it refuses to run on the infected computer try changing the name of the program, after installed, from hijackthis.exe to scanner.com in case it's one of those trojans that recognizes it and tries to stop it from running.