It could be just a loose connector on the back of the computer.
It could also be malicious software. Scan the computer with a virus checker.
Otherwise, it could be either the monitor or the video card in the computer.
Try the following to find out which:
- Swap monitors with another compatible computer, and see if the trouble stays with the computer, or goes with the monitor. If the trouble stays, replace the video card. If the trouble goes, replace the monitor or have it repaired.
- Arrange the power connections so the monitor stays on when you shut down the system. If the trouble goes away when you reboot, then you need a new video card (much cheaper than a monitor). Please rate our solutions and if you still have problems please call back for more ideas to help you
Thanks Richard Scott Technical Support New Zealand