Monitor in power save mode

Hi,

I have an Optiplex GX260 with a 1702FP monitor.  These are connected with the standard 15-pin analog video connection from the on-board graphics.  Occasionally when you power up the PC, there is no image on the monitor, and the leds on the front of the monitor show it is in standby mode.  When i press a button on the monitor a message appears saying 'Power Save Mode, Move the mouse or press a key to exit' (or something similar).  However, doing this does not resolve the problem.  Even when the PC is then powered down and then up again, the same problem occurs.

The only way to rectify the problem is to remove the power cable from the PC for 10-15 seconds, then restart the system again.  After this, the picture is displayed as normal and all is ok... until the problem occurs again!

Whilst i can temporarily resolve the problem, it would be nice to get it fixed permanently.  Does anyone know how to fix this?

Thanks in advance!

Graeme