I need major help with ComboFix.

Hello, all.

I am currently trying to get rid of some malware on my computer, but I cannot do so until I have a log from ComboFix. However, when I let ComboFix run, it does its usual scan, restarts the computer, and then a 3M window comes up and says something like: "Preparing log. Please do not run any other programs until ComboFix is finished." The first few times I let it run, I quit ComboFix after about an hour or so. But then I thought I would just be patient and sit through it for the long haul. The problem is that as of my most recent run, I have let it run for 21 HOURS, literally! Does it usually take this long? Am I not doing something right? The working lights on the desktop are only blinking minimally, the way it would if I was just not running any programs at all.