You can also try this - http://www.majorgeeks.com/files/details/unlocker.html
Since most USB flash drives are formatted with FAT32 or exFAT, there are no permissions involved, so the failure to delete is the result of the file or directory being in-use and locked, which is why an unlocker utility worked.
In this case, though, I would've used Process Explorer (which can also "unlock" things with its ability to forcibly close handles) so that I could see what it is that's creating and using these files/directories. Because they do look suspicious, don't they?
All AV is about as effective as airport security. Far too many people take a "my AV will handle it" approach when AV is really a last-ditch line of defense more akin to airbags in a car--there's a good chance it won't actually catch what it needs to catch. You'll find that I have a very low opinion of all forms of AV.If it was something nasty my AV would have catch it.
That's unlikely. Leftovers are just that: leftovers. They don't have open handles on them that prevent them from being deleted. If you had to use an unlocking program, that means that a program that is currently running on your computer has an open handle to that file. That doesn't sound like a leftover.Anyway, I think that it's more likely as Dahak said: some kind of stupid leftover.
If it was something nasty my AV would have catch it.
