Memory issues - kernel panics / system freezes with 1Gb Memory Card

Question

I've recently updated my PowerBook OS to 10.4.7 and now more recently 10.4.8.
Prior to this, i had been running a pair of pc2700 memory cards (1x1Gb + 1x 512Mb) bought from crucial technology on 10.3.9 with no problems.
During the upgrade, i experienced complete system lock ups and kernel panics. pulling the 1Gb card resolved the problem.
So i thought it could be duff memory (it happens). I ran hardware checker, both long and short tests, ran memchecker from single user and there was no reported errors although i was still getting crashes.
I returned the memory to crucial and they replaced it and then i went to reinstall memory in the pb.
Once reinstalled, problems re-emerged. Both System profiler and iStat pro show both memory sticks as ok. both are pc2700 DDR.
i tried just the 1 Gb stick in alternate memory slots. with the memory in the lower slot i was getting system freezes, in the top slot i was getting kernel panics.
I've pulled the 1Gb and reverted to 768Mb (512Mb lower (crucial)/ 256MB (apple) upper) and i'm back to normal.
Now what?
As my mac is getting on, i'd like to get as much RAM in it as i can, ideally the 1.5Gb /2Gb which it can support. I'd be suprised if it could be the memory stick being duff (2 duff in a row?), its not a faulty memory slot as system profiler is showing that its full.
Any suggestions? Anything to do with how 10.4.8 handles the memory addressing?
Any help would be appreciated.
PowerBook G4 1Ghz FW800   Mac OS X (10.4.8)  

Answer 1

I've had that problem, too. I found out that it was one of my memory modules that were broken.
I'd say pop back in your other memory module, then get out your PowerBook DVD and stick it in Restart your PowerBook while holding down the Option Key on your keyboard until some buttons start to show up on your screen.
Select the Hardware Test one, then click the Arrow button. It'll boot into a utility and you can run a hardware test that includes checking your memory.
If any of your memory is bad, it'll show up like "**ERROR ERROR**" and give you a code.
After you've identified the hardware problem (hopefully just the RAM), then you can go to Crucial's website and fill out an RMA request to have the memory replaced. I'm pretty sure Crucial has a life-time warranty on their memory products.