Hi. Someone
else was getting the same error message when
deleting files, which may be a result of having too many programs open and not enough RAM (memory).
It's worth trying to close unused programs, however I doubt it'll fix it because you're not
trying to delete the files like the other person.
Check to see if you have enough free space on your hard drive.
The only other logical reason would be a program blocking it, as djdannyp suggested. Try disabling McAffee, see if that fixes it.