[G4] Overheating G4

[Steve Jensen]

Hi Folks,
My daughter has a 15" G4 1.67, X.4.10 that is running so hot that she 
cannot use it on her lap. The fans no longer run at all!   The bottom 
toward the back is very hot to the touch.  It started this a couple 
weeks ago.  Previously the fans ran and the case was only warm.  So far 
operation of the G4 does not seem to be effected. Is this hardware or 
software? Should she stop using it? Will this temperature cause damage 
and if so, how soon?  Any remedies and ideas would be greatly 
appreciated.

tia,

Steve Jensen