Windows 7: Unable to rename music folders

This problem has been with me a while and really drives me mad sometimes.

I try to change the folder name and it reports that I cant as the folder or file is open in another program. Ive no idea what program because Ive not listed to it since rebooting the machine. I tend to use winamp rather than wmp.

hmm I notice that wmpnetwrk is running at times. Is there a way to make that process scheduled so it runs at night?