Please excuse my noobidity. My Macbook OS 10.4 has been running very slowly. Free disk space is scarce, despite the fact that I have only 3 gigs of photos, very little music, and no movies. OmniDiskSweeper shows me that a lot of space is unaccounted for. My dad suggested I repair disk permissions, and then run DiskWarrior to fix the various problems afflicting my lappy. Permissions repair went fine, but I can't run DW. It says that it can't find even 288 megs of contiguous disk space to temporarily store everything on my hard drive while it writes and optimizes the new directories. I've read that this means the disk space is so terribly fragmented there's not even 288 megs of space anywhere that has not been broken up. I've asked my brother about this problem, and he says that macs don't fragment in the first place. He suggested that I back up everything and erase and reinstall the OS. But my dad calls that an extreme option and says a lot of things can go wrong in that process. ("Let's not kill the mosquito with a bazooka," he says.) I'm not sure what to do. Should I try defragmenting? If so, what program should I use? I don't want to zero out and reinstall unless it's my absolute last option. I'd like to hear about other, less risky options that will either fix my lappy and get me all my space back, or give me enough contiguous space to run DW. Thanks a lot.