I have quite a big D drive (a separate disk) on this computer - 149 gig with 89 gig free space - and I can't defrag the D drive.

I get "insufficient memory" "try closing some programs" - which is no use if tehy are all shut already.

Suggestions?

I might have a very old Norton Tools lying around (not loaded) but it might be so old it only plays with W95! My recollection is that it puts the essentials at the other end of the drive from the Windoze (all right, MS-Dos) defrag so you don't want to alternate them!