Okay, I know all the arguments for and against defragmenting Mac drives, but I do have some pretty nastily defragged partitions. I do have iDefrag and that always worked well, but I just bought Drive Genius 3 recently (and it helped me fix my wife's iPod drive!) so I figured what the hey... Thing is, every time I run the defrag on ANY partition on ANY drive, I get the progress animation for a while, but then the screen goes black and I can't do anything else unless I force the power off. Last night I started a defrag on a 100-gigabyte partition and after about 15 minutes I went to bed. Still had the animation at that point. But at this point the MacBook is still on, but with a black screen and the fan whirring away. Is this....normal??? FTR, I'm doing this on the MacBook mentioned on the side of this post. I have a quad boot (Lion, SL, Ubuntu, Win7) and this happens whenever I boot to either Lion or SL and try to defrag anything. Haven't actually run defrag from my iMac, though -- too new...only had that a month and it's still blazingly fast, hardly any use compared to my MacBook.