Help Guys!

I'm using Dell Latitude 610 with windows XP SP3. Here is the problem:
I cannot run my diskdeframenter "disk defragmenter could not start"
that is the error I get everytime I'm trying to analyze or defrag a disk.

I've already tried full scanning of my drives with different antivirus several times including microsoft "onecare.com" I've also tried scandisk in command prompt: chkdsk /f and chkdsk /r as I red in one of the forum.

Still no avail, any idea will be appreciated.
Thanks a lot.