2407FPW DVI input partial failure

I have a 2407FPW monitor and have happily been using it for a couple months. I use the PIP functionality a lot with my computer and cable tv set top box (DVI for computer, component for set top box). At times, I connect the DVI cable to my cable box for a more digital picture (best for 720p shows).

However, yesterday when I moved the DVI cable back to my computer from the cable box, no video showed up on the monitor. The monitor detects that the cable is connected, but almost immediately goes to power save mode. If I disconnect the cable, the self-test display comes up. I reconnected it to the cable box and verified that the DVI input was still working from the cable box. I have done a ton of troubleshooting and cannot figure out what the problem is.

Tried doing the following:

- VGA output on video card still works, VGA input on monitor still works (7800 GS OC)
- connected DVI-VGA adapter and verified the DVI output of the graphic card is still functional
- rebooted computer
- reseated card
- shut off computer and unplugged power and turned it back on
- powered off monitor for a few hours and back on
- unplugged monitor for a few minutes and back on
- tried a different card with dual dvi output, straight DVI did not work, DVI-VGA adapter worked (6600GT)
- checked the DVI cable pins, none are bent or broken

I am at a loss as to what the problem is or what I can do to fix it aside from contacting Dell and getting a replacement monitor. Any ideas on how to completely reset the monitor (maybe something got corrupted in it?).

Thanks for your help.