no matter how long i let defrag run, it never "completes". why is this?

You're asking for tech support, which is not the purpose of the computer security forum. Our focus is on hacking and cracking machines. I'm going to move this to Technophiliacs and Technophiles.

You also didn't give details like your OS, the defragmentation program you're using, and what else you're doing while the defrag is running.

Run chkdsk on drive.
And then run Defraggler (a Disk Defragmentation software which is FREE and it works). It will complete.

Run chkdsk on drive.
And then run Defraggler (a Disk Defragmentation software which is FREE and it works). It will complete.

This.