XP won't fix errors on a MyBook drive....

Its Windows XP SP2 and its an external USB MyBook 500 gb drive. The
files/programs for the most part are working on the MyBook drive, but
in one directory, there are corrupted files becasue of errors. THese
files cannot be moved deleted, copied or anything when I try. I went
to H: properties/tools and checked box to have Windows scan/fix errors
on the drive. It says it can't do that because it has to have
exclusive access ....do you want to schedule this for the next reboot?
I check YES and exit the tools utility. Reboot system....nothing
happens when Win XP boots up! SO how can I get this drive
straightened out?