Disk utility hanging I'm trying to reformat the hard drive on an iMac G5 prior to selling it. I've booted the Mac from the installation DVD that came with it, opened Disk Utility, and told it to erase the drive using both security options for zeroing out and rewriting the data. However, Disk Utility seems to be hanging: I let it run for over 12 hours and it didn't finish; I needed to unplug the Mac and restart it (the program wouldn't even let me force-quit it.) 

I started the process again, but it still seems to be going extraordinarily slowly. Is there something wrong with this, or does it just plain take a long time? I'm not hearing the hard disc spinning; it sounds like it's hung again.
How big is your hard-drive? It's entirely possible that it would be normal for zeroing out the sectors to take that long. I'm only extrapolating here, but I've had secure-deletions of the trash take an hour or more for a few gigabytes, so if the hard-drive is large, I could see it taking quite some time.

The other thought is that there is some problem with the drive that prevents the format from completing. You might want to check the drive for errors and/or bad sectors. It is possible that you would have eventually encountered the error on the hard drive yourself (potentially causing instability, data loss, etc.).

Finally, if you look at Activity Monitor, does it look like the disk utility is doing anything? Check your disk I/O statistics there as well and see if anything is still going on with the disk in question.