Question : Problem: Dell Optiplex w/ Radeon X1300Pro has problems using dual monitors

I have a user with a Dell Optiplex and an ATI Radeon X1300Pro video card.  He is attempting to extend his desktop across two Dell 1707FP monitors.  Sometimes it works (but one monitor usually flashes) and sometimes only one monitor works with the other monitor displaying a message that reads:

2: Digital input cannot display this video mode
Optimum resolution 1280x1024 60Hz

It appears to be a refresh rate issue, but we have not been able to permanently resolve this.  Sometimes it works, sometimes it doesn't.

We've tried changing cables, the adapter and even a monitor.

Answer : Problem: Dell Optiplex w/ Radeon X1300Pro has problems using dual monitors

After all of the testing and changes it turned out to be a faulty card.  

I replaced it with the same card out of an identical PC that was working and it worked fine.

Dell is sending me a replacement card under warranty.

Thanks for the suggestions.