Laptop problem

[T ® ø õ p ê R]

Lo all, i'm having a bit of trouble with my laptop. Its a HP Pavilion zd8000, if i turn the laptop on without the mains adaptor (running on battery), after the windows logo screen (running windows XP) the screen goes black, so i have to turn it off and plug it in or reset it to get windows to boot properly. Also when i'm using the laptop without the adaptor i get a lot of BSOD's mainly when using windows media player and running quite a few programs. With the laptop plugged in to the mains, i don't have these problems at all. Could anyone help? I'm not quite sure what to do.
cheers

 

[T ® ø õ p ê R]

It's a new laptop, haven't had it that long (few months). It does get quite hot, but seems to be fine when im using the mains. It's been like this since i bought it really, sometimes when the laptop is on and i unplug the mains, i get a BSOD. Dunno whats wrong with it.