The Hewlett Packard monitor I purchased in February 2004 has developed an intermittent fault. The monitor works O.K. for a short time after being switched on and then the power supply turns off and on very rapidly. The processor does not appear to be affected. My initial thought is that there may be a simple answer, such as a faulty adapter, but I would welcome other possibilities.
If not I would suggest you take a look and make sure the problem doesnt occur when using another monitor (borrow one for a while). It could suggest graphics problems also, best to eliminate where the problem is before starting the whole warranty thing off.
make sure the vga cable is pushed fully home into the socket on the back of the pc, and the socket on the back of the monitor (if there is one). Same for the power supply cable. Wiggle them about a bit when the thing is running to see if it's a dodgy connector.
Does the monitor take it's power from the mains directly or from the pc?
Does the on / off thing happen just once, or is it repeatedly. Is it accompanied by any noise?
Sorry for the lengthy period of silence but my intermittent video problem is still unresolved. A Service Engineer suggested a manufacturing defect and I am currently pursuing this with HP. The period of warranty was 12 months only but because of the defect in some cases it was extended to 27 months. My monitor was purchased 29 months ago! I will post the outcome in due course.