It's possible that the Bagle infection has corrupted some of the files that are needed, you can either do a repair install of Vista, or try and replace the relevant files.
Unfortunately you are now outside my area of knowledge, so I'm going to have to recommend that you visit one of the tech forums for assistance.
http://www.techsupportforum.com/
http://www.bleepingcomputer.com/forums/
http://forums.whatthetech.com/forums.html
All the forums above have good support for software/OS problems, and I'm sure they will be able to help.
When you start your thread, explain what the problem is and let them know that you have been checked for malware.
Give them the following link, so they can see the logs if needed
http://malwareremoval.com/forum/viewtopic.php?f=11&t=33372