PowerBook G4 12" Memory issues

[matrixj]

Hi, I'm working on a client's 12" PBG4 867Mhz (PC2100). He brought it to me about 3 months ago because it was freezing constantly, it would even freeze when I would boot it in Target Disk Mode to my laptop to back it up. It would also halt my system when it did that. I was thinking some sort of power issue but I had some spare memory from an iBook that took the same type and that fixed everything.

Now, he called today and it's doing the same thing. Would it simply be coincidence that the iBook memory went bad as well? Or is something frying the memory each time? And if so, any ideas what? The internal memory is working fine. I ran memtest without the extra stick in and all tests were good. I'm currently running memtest with the extra stick in and waiting on it to finish because it's taking forever. But, I've obviously figured out that it's the extra memory again. I just don't know what to recommend next. Purchasing new memory this time and wait a few months to see if it happens again? I'm open to all opinions and suggestions. Thanks in advance.