USB drive gets infected every time I plug it into my laptop

"For unknown viruses and stuff I use sysinternals.

With Process Explorer try to find strange process (or a process that has a handle on the EXE file in the cache folder.)
With autoruns look at everything that is starting automatically. Remove suspicious entry's.

Be careful, before removing anything. Google it, it might be needed. You can wreck your system this way. Advantage of this is that you also might find that you have some kind of program running that has this behaviour, and all you might have to do is uninstall it.

Hope this helps."

"Before giving up and reformatting and reinstalling Windows, here are some more options:

Google for ""antivirus online scan"" and use a couple of the best-known ones to scan the computer (each takes some hours to complete).
Some that I like are Trend Micro House Call and Kaspersky Labs Free Virus Scan.
Please note that they might require you to use Internet Explorer as your browser
Use a rescue live-CD virus scanner : I like best Avira AntiVir Rescue System because it gets updated several times a day and so the download CD is up-to-date.

I once had an infection problem, and I ran quite a few scans before I found the one that succeeded in finding the virus.

You're lucky in the sense that's quite easy for you to verify if the virus was really eradicated."

An application called UsbFix, as generic as it might sound, seems to find and clean and restore USB devices messed up by some USB or shortcut virus which aren't detected by normal antivirus applications like Avast.