I'm kind of the default "go to" guy for all PC issues with friends and family. One of the most common problems people bring to me is malware. Going forward, I'm going to document the removal process for some of the more difficult ones I encounter. The most difficult trojan I've encountered thus far is the sirefef.AE trojan. It infects the PC by replacing c:\windows\system32\services.exe which is pretty ingenious in that it's extremely difficult to remove since Windows requires it and it's always in use which keeps the antiviruses and applications from being able to remove it. I just spent a few days battling this one and successfully cleaned it off the system. To remove it: