Thanks a lot for all the suggestions - unfortunately, none of them helped.
It's a 2 GB stick. I tried it on several machines (WinXP and 7), including the one I last operated it on. Unfortunately, the boot sector of the USB stick was damaged, and I was unable to restore it.
So I formatted the stick and used a data recovery tool (Recuva) afterwards. I was able to restore almost all the data. Except for the few files that I did not have a backup for. This Murphy guy was an asshole...
The files in question were the winner certificates for our May and June photo contest winners, which I finished only yesterday and thus did not have a backup for yet. No data is lost, I still have the certificate draft and the photos, but of course, it takes some time to embed the photos to the certificate and update the photographer names.
So, you guys will have to wait a few days more. And I learned a lesson: never save something to a USB stick without IMMEDIATELY making a backup.
Btw, so far I was one of the careless guys who just unplugged the stick after use. I will write 100 times "I shall use the 'safely remove' function" now, and no TV for me tonight...
Ideology: The mistaken belief that your beliefs are neither beliefs nor mistaken.