Be sure to check the Apple doc cited by kbear as the routine varies according to your model of PB.
http://docs.info.apple.com/article.html?artnum=14449Other things to consider regarding the printer and your adapter includes the possibility that the surge protector may be faulty. Also if your removeable battery in the PB is not being recharged due to its being old or a flakey adapter, the PRAM battery will not be able to maintain its charge either. Most of those batteries only have enough charge to hold the date/time for 5-10 minutes if the removeable battery is not charging it or it is not on the AC.