Defrag problem W2k-Diskeeper?

OS: Windows 2000 SP4

Defrag Program: Diskeeper V9.0.515.0

RUN: manually

Drive: C:\

Type: NTFS

I am tring to manually defrag drive C:\ , and I get the message that it has detected that CHKDSK is scheduled to run on the volume, due to either a user request, or because the operating system has found errors in the file system. CHKDSK will run automatically during the next reboot, until CHKDSK is run Diskeeper cannot degragment this volume.

So I close Diskeeper, and do a reboot, but it says that it cannot run CHKDSK, because other task has control on the volume.

I think I have a switch or something "on" in the registry .... but I don't know were to check it, or if there is other ways to turn it off.

I have try the DOS command CHKDSK and CHKNTFS without any result. I also used the FSUTIL (DOS WinXP utility) (I got it and copy it in my PC)

What should I do? Thanks for the help