Last Friday my main computer started exhibiting some odd behavior. The case fan was running full tilt all day long, and response from other applications was slow. When I looked at Task Manager, I saw that the System process was pegging out at 99 percent and making it impossible for any other app to work properly.
I followed my own advice and used Msconfig to narrow down the problem. It turned out that PC-Cillin Internet Security 2005 was the culprit. This Trend Micro Knowledge Base article acknowledged that I wasn’t the only one who had been hit by this rogue antivirus pattern file, and it gave me the fix, which involved booting into Safe mode, removing or renaming some files, and then restarting and updating PC-Cillin.
When my notebook started displaying the exact same symptoms this afternoon, I was able to fix the problem in a few minutes. If you’re experiencing a sudden slowdown and you use Trend Micro’s security software, you know where to look. (Their article says the problem is caused by pattern file 594, but I found that my notebook, with pattern files 586 and 596 on hand, was affected.)