My iMac has been cranky ever since I installed 10.2. Lots of spinning beachballs, abrubt Finder relaunches, etc. Tonight I finally got around to running Disk First Aid. I got about three dozen "overlapped extent allocation" errors that weren't fixed after trying to repair the disk multiple times. Some other errors were fixed, and so far thing are running a bit more smoothly. But what is this "overlapped extent allocation" stuff all about? Do I need to try to fix it? How?