Need help with iBook G4... No display and freezes at random times

Hi, I've been searching all over the web and could not find anything that's the same as my issue. I have a 1.33ghz iBook G4. It decided to freeze up on me one day and so I rebooted the laptop. Since then it would start up but the screen wont show anything. You can see the backlight of the LCD is on but nothing more is showing up. Further more the laptop boots up into OS X 10.5.2 as I can hear the sound from changing the volume etc. On other times the LCD would start working if I leave it on for 20 mins or so but then it would freeze only to restart and have the same problem again

Does anyone know what is causing the problem? If so...is there a fix?

Thanks
Shifty