Windows 7 Boot Camp Partition Won't Defrag

Hi folks, I recently installed Windows 7 64-bit via Boot Camp on my Mid 2011 27 inch iMac so I can boot into it for gaming.

I am having issues trying to defrag though. I have tried using the standard Windows 7 defragger, which says the drive is 21% fragmented, but when I run it, it starts to defrag but then just stops and shows 21% again.

I have also tried third-party defragging programs like Defraggler and it pretty much does the same thing.

I set my Windows 7 partition in Boot Camp to be about 350 GB. I have installed Windows 7 before via Boot Camp on other Macs in the past and haven't had this issue.

Anyone know of any solutions? Any help would be much appreciated.

I have already ran a checkdisk and scandisk for errors etc.