Troubleshooting MBP with external display

I have an older MPB with a DVI port (no adaptor) running OS X 10.6.7. I've used a dell monitor with it for a couple years with no problem. Today, The screen was black when I sat down at my desk. The light on the power button is green, which means there's some type of connection (it's orange in the power save mode).

If I click "detect display" in the system preferences, the monitor will flash on for about 2 seconds, then go black again. The power cord is plugged in on the mac (I know that can be a problem) and I don't see any loose connections. I've tried 2 DVI cables with the same result.

Anyway... I'm trying to figure out if it's the monitor or my computer or a software setting that I'm missing.

Again, I've used these two in combo for 2 years with no kinks until today.

Any thoughts?