Here is the scenario: PB is about 3 months old now. 2 sticks of 512 RAM in it. 1 came with the machine, 1 I bought from a guy that had a new PB, same as mine. He was bumping up to 2G RAM. I have been having panics lately. I talked here and called Apple. Apple thinks its a bad stick...of course the think it is the '3rd party RAM' that I put in. I explained to them....why, I dont know, but I explained that it came from a duplicate PB of the same age etc. Boy, I dont like Apple as a company. That is another story though. I pulled the added stick out (B) and I pulled the original stick out (A). I then swapped them around. B where A was, A where B was. It booted, but only showed me 512. Thats odd. Pulled them again, reseated them, booted....512 again. I then pulled out stick A and it booted fine. Same with stick B, booted fine. I then put them back in the original order and booted, 1G it showed. Tell me why I cant swap these 2 sticks around?