I have noticed that a lot of times if I move my 15" iBook G4 abruptly, it will completely shut off. The first time it happened, it was sitting on my bed and I sat down and turned it to me, the second time, it was on my sister's dining room table and she turned it to type something, and the third time, last night, I was setting up internet sharing on my friend's ibook, and I switched back and forth between the two a few times, and then one time I grabbed mine to pick it up and it just shut off. I tried doing the same thing to her's and even tapping it, and I didn't have any problem. It's never really been any more than a nuisance as it's my mother's computer and she never touches it and I only use it as a backup to my Mini, but I'm worried that one day I'll be doing something important and I'll lose it (not that you cared to know my life story, right?).
Has anyone else ever had this problem though? And what should I do about it?