Weird problem: we have a number of external drives (Freecom ToughDrive 320GB USB) for backup purposes. When connected to any of a number of XP or Vista computers, or a server running Server 2003 standard, they work fine, assigning a drive letter (usually F:) to the partition. There's also another 1MB drive that shows up as a CD-ROM containing password software, but that's not relevant (at least I think it's not).
However, plug them into one of the two servers we want to back up (both running Server 2003 R2 Enterprise) and the no drive letter is assigned. You can assign one manually, and everything's fine - until you remove the drive and reconnect it, when it has no letter again.
There are a couple of mapped drives, but plenty of spare letters. We need to be able to have a non-admin user swap the drives, and this isn't possible if you have to manually assign a drive letter every day.
Any ideas? Thanks in advance.