W2K Defrag

Heres my problem (besides using windows)I want to set the defrag to run at a certin time I setup the windows task scheduler to run defrag at night once a day and thought I was done. Well Bill & co. done it again it will bring up the program but it just sets there an does nothing any one have solution to this with out haveing to get third party software I have nortons system works but dont like speed disk