I have a new Dell XPS with an NVIDIA GeForce GT 445M and an old (several years) Epson PowerLite Cinema 550 projector. Windows 7 refuses to recognize that the projector is connected under normal conditions (I'll get to the strange condition in a moment). Here are some things that I have already tried:

1. Confirm that the projector continues to work well on my old Windows XP laptop.
2. Confirm that the video cable (HDMI to HDMI) is connected
3. Make sure the Dell laptop is plugged in to wall power at all times
4. Reboot both the computer and the projector
5. Click "Detect" under the "Connect to an External Display" Windows dialog (no reaction)
6. Click "Rigorous Display Detection" under NVIDIA Control Panel (dialog: none found)
7. Checked "Force Television Detection on startup" under "My display is not shown..." in NVIDIA Control Panel (no effect)

Here's where it gets weird... My projector has three states: off, standby and on. Standby means the power switch on the back is on, but the projector is effectively off (no picture, no access to menu or controls). When I plug in the HDMI cable while the projector is in standby, Windows detects the projector! It lets me switch to Duplicate, Extend, or Project Only mode, and adjusts the resolution appropriately. A new Generic Plug-n-Play monitor shows up in my device manager. A "Seiko EPSON PJ" display shows up in my NVIDIA control panel. Then if I turn my projector on, Windows no longer recognizes the display. This is true whether I turn the projector on while the HDMI cable is plugged in, or if I unplug the HDMI cable while turning on the projector.

Anyone have any ideas, because I'm completely stumped...?