Quadro FX 540 - DVI output failure TWICE??

Hello all, having a problem here that has now happened for the 2nd time.

About 12-16 months or so ago, I was cleaning out the dust from inside my tower case. When I hooked everything back up, suddenly the DVI output on my PNY nVIDIA Quadro FX 540 seemed to have quit working. My monitor kept saying No Input on the digital input. I had to switch to analog VGA for awhile, which looked pretty bad on my 1680x1050 Viewsonic display.

One day I happened to be in the office of the IT consultant my company uses, and happened to mention my problem to the owner. He graciously let me take another FX 540 card they just happened to have laying around and not using. I swapped the cards, hooked up the DVI cable, and all has been fine since then.

Until today. Now I just put in a 2nd HDD into my tower case. Got everything hooked up, powered it up, and BOOM nothing on the monitor's digital input.   What the heck could be going on here??? I never even touched the graphics card at all!! I don't understand why the digital output of this graphics card keeps going out on me! Do I have any course of action or any way to test or troubleshoot the situation?

I really can't afford to drop another $150+ on this machine. I had a catastrophic HDD failure last week and have just put quite a bit of money into the machine to get it back up and running. Any help would be most appreciated.