partitioning - How to determine non-movable files in Windows 7?

Is there a way to determine which unmovable files are preventing Shrink Volume from releasing the full potential free space?

Background:

I have a 90 GB partition with Windows 7 on it, and 60 GB free space. I want to shrink it down to about 40 GB, and use the reclaimed 50 GB for a separate data partition. The Shrink Volume tool in Disk Management is only willing to give me 8 GB back.

My understanding is that this is because of immovable files. I've followed the instructions found here, which involved disabling hibernation, pagefile, system restore, kernal dump, making sure all related files were deleted, and defrag'ing. I have successfully followed those same instructions before on this same drive, and partitoned the original 150 GB space into 90 GB and 60 GB, but I'm not so lucky this time.

Answer

I think you can use Defraggler (free) - http://www.piriform.com/defraggler

Just click on a block to see the files.