What operating system are you using? If it's Vista, then there remember that there is no display for the defragger so you really can't make out what it's doing.
Maybe there is a file system error preventing the defragmenter from running. Run chkdsk once on the drive to make sure. Instructions here click here
Best option is to try another defragmenter. I suggest Diskeeper 2008. It's the best of the defragmenters I've tried, and I use it on both my systems. It does a great job in defragging the drives using only minimal resources. (Try the auto defrag mode for best results). You can grab free trial versions from click here
This thread is now locked and can not be replied to.