Hi Jim,

Here are some questions that I would start with:

1. How long have you had your current setup without a problem?
2. Have you installed anything prior to the problem occurring - any new software or updates?
3. Did you also update the drivers for the monitors?

I have read extensively about other Apple users (not just those using Mac Pros) using dual monitors having similar problems as yours and there does not seem to be a general fix. However, the above suggestions are a good start to finding a solution.

You can also try these even though they may seem trivial. Sometimes it is the simplest thing that is overlooked that is the problem:

1.Checking your power cables first to make sure that they are working properly/not loose/not damaged - if you have a spare switch cables.
2.If you have more than one port try connecting to a different one (i.e your dual link DVI port).
3.If you have another computer perhaps a PC (or have access to one), you can connect the dual monitors to the the other computer and see if the monitors behave the same way or is also not working properly in some way- this will confirm or rule out faulty monitors - it is a hassle and a lot of work to do this though.
4. When your monitor is flashing have you tried to adjust the monitor settings to see if it would stop?

Just a few ideas. Sorry, I can't be more helpful. Keep us posted about what you did and if anything worked.

Good luck,
Chanthee

Jackie may seem sweet and she is but don't be fooled...she is 9 lbs of rage!