I just wasted over 20 hours running Tech Tool Pro 4 on my 160 GB disk drive in my dual G4/800. It found a rather nasty, but not crippling problem. I don't even remember the error--it's been that long. The application apparently crashed before it finished with the repairs but thankfully, hadn't gotten past the point where I would have clicked okay to apply the changes. Is DiskWarrior significantly faster?