pc turns on but the monitor

Gday

my friend here has a pc a normal P4 (3.0 guess) 1GB ram well the problem is when he turns on the PC it turns on fine the POST (power on self test) works fine but there is no display on the monitor
when disconnect the monitor cable the monitor does a self diagnostics and that seems working

if this happenes he turns it off on off on off on a few times and suddenly he get the display

It works for a few days and then he has the problem again then comes the ON/OFF ON/OFF ON/OFF ON/OFF ON/OFF ON/OFF untill it works

Can some body tell me why it happens and what is the solution for it

thanks
Ram

Check if the monitor cable is faulty.

This happened to a friend of mine ... we changed the AGP and it is working fine now

i will ask him to check the cable

the agp i onboard one so he cannot change it

Ram

Try using another AGP card