If Disk Defrag can't run, then your file system is corrupted. Don't panic.
NTFS file systems are very tolerant. In the meantime, the less you do on
your system the better. After you fix the file system, you may have to
re-install any software that does not run properly.
Hello Brian,
If you have Norton Personal Firewall 2005 installed on your computer that is
the cause of not able to defragmentation and check disk for errors.
Kind regards, Michael.