laptop blanking

[Barry Marchant]

Hi all, I have a compaq nx9040 which I wish to use for a continuous 
slide show this weekend but I can not stop the screen blanking.

I am using kde, running on mains power, Display power control not 
enabled, blank screen saver selected & set to start after 500 mins (over 
8 hrs)

What have i missed which is permitting screen blanking

TIA

Barry