Chkdsk will not run after reboot

As the title says when i go to start -> run -> cmd "chkdsk/f" and hit yes to do it upon reboot it just doesnt happen, its a problem that has plauged this computer since i got it (HP Laptop (HP Special Edition L2000)), I found a guide that menioned it may be antivirus software or other software that requires exclusive access to the MFT, and NAV 2004 was presintalled on this computer and since then removed for awhile now. I dont have any other antivirus software or tuneup / disk maintence software installed. Can someone point me int he right path as to what i should do, my hard drives corrupt and some apps wont run properly ex: (svchost.exe keeps crashing (On and off problem sometimes it happens sometimes it doesnt), upon boot i get a windows DEP error on explorer.exe (pretty much everysingle time)).
Is it a possiblilty my Norton uninstallation didnt remove everything?, Is there possibly another program i could use for chkdsk?
(EDIT: Running Windows XP SP2 with all updates)

Greatly appricated.

 

Thanks man, that solved it.. the problem was really screwing me up.