The iBook does not have a backup (PRAM) battery. It only has the main battery and a small capacitor which maintains the settings long enough to do a battery swap. If the battery is dead, what you are seeing can happen.
If the battery is not a problem (or even if it is), you could try resetting the PMU and see if that helps.
thank you ronda for the post. i will try it and see. one thing i have noticed is that i still have the battery charged when it happens. the bar will be half way down. it won't let me turn back on until i plug in the charger then it starts up. if that makes sense,
thanks for the post.. will try it and post back.