It's definitely Vista upgrades which have something against it. I have Buffalo's HD-CEU2 Drivestation TurboUSB, which worked just fine yesterday, until I patched my Vista. And now it says that I have to format that hard disk, before I can access, fix, or even rename it. I really DONT want to do that, for theres some vital data inside, which's recovering is a hard task in itself. And the external drive was solely meant as a storage device for me anyway. So if I format it now, lose all the data, painfully get all the data back there, theres always the possibility it may do that AGAIN, which kind of kills off the idea of using the hard drive in the first place, if you constantly have to keep formatting it.
I havent tried it on my friend's older XP-computer though, but the problem is definitely with Vista's updates. Some sort of a constant solution for this problem would be nice. Other than clearing out all the data.