[Defraggler freezing computer]

Both Piriform Defraggler and Windows defragmentor are freezing my computer when running individually on my computer. How can I fix this?

[Defraging slowly]

The past several times when I defrag my computer using this program, it takes an incredibly long time to defrag. Last night alone it took roughly 7 hours to defrag. This has been going on for about a month or two. It seems like it has a not time defragging bigger files that are several hundred MB's or bigger. This needs to be corrected. It shouldn't take more than 3 hours or so to defrag a computer especially when it has about 47% or so of free space.