So I just thought I would share with everyone else about my RAM issue on an iBook G4 1.33 Ghz, 40 GB, 1.5 GB RAM. Well, in About This Mac, even though I had and additional Gig installed alongside the 512 MB on the motherboard, it said 512 MB. So, I booted up from the install DVDs, and ran an extended hardware test, and a short hardware test. On both the tests, it said the RAM passed. But, when I first booted up, it said it detected an error with the hardware. I figured it was the removable RAM. I shut down the laptop, and removed the RAM. I had two sticks, and I knew it wasn't the motherboards RAM causing the issue, but it still said the same when I booted up. Because it booted up fine with no other memory installed, I began to investigate the RAM slot. So I began to check for dirt and dust clogged in it, and discovered something. I know its not just on my particular model, it's the same on a different iBook G4 motherboard I have. The memory may look like it is in, but you really have to make sure it is all the way in: it's a tight slot, and if you think you have the RAM in all the way, make sure you can just push down on it to latch it in place, otherwise you know you have an issue if you have to push hard or something like that. I booted up the laptop after correct installation, and it showed up as 1.5 GBs! I just thought I would share, because it had me stumped for a while.