XP Not Running Chkdsk or NDD on Bootup

Hi:

Trying to get either Chkdsk or Norton Disk Doctor to
run a scan on reboot of my system. I schedule them to
run on reboot but it does not happen. I checked the
registry entry for autocheck and it seems fine. Is
there some file or other registry setting that needs
to be changed. The fact that neither one works leads me
to believe it is a system program, file, or registry
entry that is messed up, but have gone as far as I can
take it. Any help would be appreciated.

regards and thanks

dan myers