I get that on occasion. I think it's actually a part of a Norton Antivirus bug in some way. Norton gives active permission to certain programs for communication and such and then when one tries to move or delete files related to these programs XP causes problems with this phantom "in use by another program" reply, if one has opened or used the file recently, because somehow it is floating in a Norton folder or somesuch.

I haven't been able to pinpoint exactly the circumstances which trigger it, but have had to reboot sometimes just to regain control of the file.

I like Norton for the security they provide but they can even make a dual processor machine move and initialize much slower than it should. Their software is not for users who like speed. I'm eventually going to go back to McAfee, which came with my comp - as it was much faster than Norton.

It may be something else, but that's my guess.