I tried to run a TechTool CD which came with AppleCare for my 12" PB. The factory original came with Panther (10.3.7). But, I did erase & install Tiger on it and it is now running 4.0.1. It seems Tech Tool CD (version 3.0.3) is not tested with Tiger yet. I am wondering what the other forum members are using for the diagnotics & repair for your Macs? Can someone comment if I can still use the original restore DVD (which contains Panther 10.3.7) which came with my 12" PB? I installed Tiger from the retail Tiger DVD; so it not running Panther anymore.