When your Mac's output to the monitor you are using does not work properly, here are some things you can try.

A common problem you may encounter with your DisplayPort, which connects the monitor to a graphics card, is called Link Failure. This is when that connection fails.

Monitor Problems A defective monitor, or one that's headed down the road to failure, can't provide a workable view of your computer's operation.

The troubleshooter analyzes the problem, suggests a solution, and in some cases even implements the fix itself. Let's see how the Windows troubleshooters can pinpoint and resolve problems.

The How-To Geek describes how Windows Vista's Reliability Monitor tracks your PC's crashes and application events over time with a line graph that can help you troubleshoot a problem.