iBook G4 Keyboard Problems

[twhounsell]

Hi Guys
i have 2 ibook g4s and one of the keyboards is playing up.
the keyboard works fine for about 10-15 mins or can play up at startup.
what happens is:
caps lock light comes on as well as the numlock light
all of the keys are unresponsive including the caps lock and num lock

i have tried swapping the keyboards over so it is definatly the keyboard

Any suggestions greatly apprieciated
thanks

14" iBook G4 1.33 GHz PowerPC