Cannot delete folder error while using Unlocker

I’m having an issue with Unlocker software. I had to use this software to delete some of my folders which were not being deleted without the help of such software. But whenever I try to delete folders it gives error
“Cannot delete folder: It is being used by another person or program.
Close any programs that might be using the file and try again”.
I would also like to mention that no programs are running or using these files. I've tried rebooting, starting in safe mode, etc. but all in vain. I have XP installed and have administrator rights. Does anyone know how to overcome this problem?
