On a windows box its generally good to reformat/reinstall at least once per year in my opinion. It clears out any bugs, such as yours, and gets rid of any malware, virii, and keyloggers that are on your system undetected because of the insecurity of windows lol.
I agree. So for my backups I only copy a designated "data" directory to my USB drive, rather than ghosting my entire drive. That way, when I have a disk crash, full disk, or some really sticky malware, I take the opportunity to wipe the disk (or get a new disk) and reinstall. Seems like about once a year per PC. That way I don't also restore the crap.
So part of my backup system is procedural: keep all my important data under one directory, and streamline the reinstall procedure by keeping all the CDs and license files where I can quickly get them.
The downside is the reovery time for that PC, even streamlined, is longer than from a ghosted drive. However, the backed up data on the USB drive can be plugged into another PC right away.
I use Second Copy to back up my data directory to the USB drive. I've heard Memeo is good too.