All right just wanted to throw in some input after digging through this thread. Installed Vista-64 on a brand new WD6401AALS and of course had to install CCleaner and Defraggler immediately after. Few days of use and after installing very large files (Steam applications) I decided to defrag my system. I noticed about half way through Defraggler would hang on a few files between Left 4 Dead 2, Dragon Age: Origins, and some random Windows files. I'd leave it on over night and wake up to absolutely no progress. As someone suggested, I turned off Vista's System Restore and rebooted my computer. Needless to say Defraggler works flawlessly now and I also shed nearly 100 Gigabytes of data in the process. Good luck to the rest of you guys, hope you resolve your issue.
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