There was an article published some time ago about the loose battery issue on some of the older Titaniums. A week ago I came across the very same problem. Armed with the information found in this PowerPage article, I finally battled my way into a good final solution. You can read about it here.
In case link doesn’t work, go the the Apple dicussion boards: Discussions > PowerBook > PowerBook G4 Titanium > Power Battery > G4 titanium shuts off when i move it .
My Powerbook is thankful that a solution was reached, as it was dizzy from all the wiggling and knocking around it got from me testing my crazy contraptions to secure the battery.