There should be information there on how to remove the infected files from your system. They saved me from having to reinstall Windows XP once after getting hit with a nasty trojan horse one time. The instructions are fairly easy to follow and thorough.
Actually, I went ahead and copied VerifierBug.Class into their search feature on their support site, and here are what SHOULD be the parameters of your trojan horse infection:
http://securityresponse.symantec.com/avcenter/venc/data/trojan.byteverify.htmlIf you don't already have it, you should look into a copy of Norton Internet Security. What that does is monitor your internet connection and alert you when someone is trying to dump malicious code onto your computer. You can also dictate exactly what programs will have internet access, so that you can avoid high-risk activity.
Also, make sure that you run Live Update for your anti-virus software on a regular basis.