Interesting that this happened with both programs, in my mind that means a file is corrupt somwhere..
Can you see which file the defragmentation has stopped on?
If not try this; Computer -> Right click "Your HDD" -> Properties -> Tools -> Error Checking -> Check both boxes, hit start, schedule a scan, and restart your computer.
Hopefully the diskcheck will find and rectify the file that is giving you trouble.
ps this will take a long time, possibly hours, and it can not be interrupted.
If you can tell which file is causing the hang-up, though, don't do the diskcheck just yet, just let us know which file it is.