Directory in use...

I installed MP3Tag 2.45a and I do not have really a "music" folder but separate folders per artists. In MP3Tag, I added the artist directory to MP3Tag so that I could edit the ID3 tags. Afterward, I went back and decided that there were a few artists I no longer wanted and want to delete them. When I try it says that the folder is in use. I can't find a way to remove the directory from MP3Tag in order to delete my folders, even after I rebooted my computer it still says that its in use. Could someone help me with this? Thank you in advance.

could you please tell a little more about your environment e.g. which Windows you use (XP, Vista, 7)?
Did you do a Scandisk on your hard drive - perhaps your fault is due to some mishap in the FAT (or the like).
Have a look at which programs start at start-up - if a folder is in use it means that some program opens files in this folder. E.g. Media Player does this while updating the watched folders.
(In general: it does not look like a MP3tag problem but a file system problem...)