Operating System: Windows 2000

This just randomly started. When I open anything on the desktop the monitor's brightness dims. The larger the window, the dimmer it gets. The Start Menu only brings it down a little, but a maximized window makes the screen too dark to even read. When I close all windows the screen fades back to normal.

I've never seen this before, any ideas?

Have you tried adjusting the monitor settings during/ within these changes?

Do you have another monitor to try just to clear the monitor as the problem?

Another test would be to run in safe mode & note the difference.

Also check Start/Run/ dxdiag | Display for any problems.

Also check the Device Manager Start/Run/ devmgmt.msc for any yellow "!"