Win XP--Can't copy to CD -- old files wont del

I tried to copy a folder from c drive to cdrom (d DRIVE).
Copy failed, which was OK as I really did not need extra copy.
BUT....when I tried to delete the "files waiting to be written" it will not let me do so stating a "file is in use".
Someplace in the computer, something is being stored which is causing this to come out each time I reboot. It want s to write the folder to cdrom but can't do so (same "file is in use" error); and I can't delete file waiting to be written.
I cant use explorer's copying program as a result, and have to copy all my files from c-->d using Nero (which works just fine)
Where is the "hidden" file I will need to erase to free up my built in cd writing capability??? how do i get to it????
Which file/files do I need to erase to put things back in original state?
Thanks for the help. .,...MaRC