I think one bank of the RAM of my PowerBook is gone. I had SEVERAL kernel panics in a few days. I ran full memory tests and miserably failed.
I removed a yucky Hynix RAM and left my beautiful-high-performance Corsair RAM and now is working nicely (3 days now).
The sad part of the story is that I am temporarily stuck with only 512MB and my Mac is DAMN SLOW! Could it be Firefox and Thunderbird that together suck up at least 70MB? Then add Mail.app, Safari, X11 terminals, iTunes, NeoOffice, AdiumX, Skype… Anything else?
I was not used to this LOW RAM!