My 2.5 year old PowerBook G4 had started acting up over the last few months - occasionally when I would restart the computer, the screen wouldn't turn on. Clearly, a laptop with no working screen is useless, but usually after a few resets it would start working again. Today, it refused to obey the power-cycling method of problem solving.

After a quick Google search (not on my laptop, obviously) turned up this thread, I popped out the memory sticks one by one. Indeed, one of the sticks appeared to have gone bad, suggesting that during the boot sequence, it needs to read/write to one stick of RAM to get the display up and running. On a lark, I decided to reinstall the bad stick of RAM in the slot that it was not originally in. Everything seems to be up and running fine, and I still have my full amount of memory. If I start getting weird application troubles, though, I know where to start looking...