why is it running hot?

[blueflame]

my 17 inch powerbook all of a sudden just started running hot. i dont know why. now the fan is always on and the thing gets really really hot?
any suggestions on why?
thanks everyone
Andreas

 

[blueflame]

ok, so i did this

i downloaded a cpu temp utility
my cpu is running on highest at 140 degrees F
the powersupply and GPU are running at 130F
is this a normal temp?
it could just be a hot day today and i am imagining it, but i swear it feel soo much hotter to the touch.
ANdreas