Okay, so here's what seems to be the issue here..
I have the same problem when I connected an external display on my laptop. (I think its an old crappy Epson projector) After a few days Win7 does not seem to recognize my laptop display (Im pretty sure its not hardware cause it works perfectly in WinXP)
All you see is black screen (this is from the time you turn on the power button so you cannot even see your bios / post options) but the activity lights are all active. Then you'll hear the Windows 7 startup sound which means that it succesfully booted the system up but of course with no display.
I tried an external LCD and it works perfectly. You can see the display from post up to Windows itself.
When i checked on the "screen resolution" option and clicked on "detect" it showed 3 displays present:
1. HP LCD - currently using
2. Laptop Display
3. Available Display on Nvidia 7000m
What I did is I disconnected HP LCD and Available Display on Nvidia 7000m (selecting disconnect this display in the options) and made Laptop Display as the primary display and this somehow temporarily fixed the problem...
It brought my laptop display back but it randomly reverts back to the original problem where it doesn't detect the laptop display at all.
I tried the bios upgrade just to take away the fact that this is an "internal" problem and also tried to upgrade Graphics drivers but again let me reiterate that this issue doesn't happen with XP as I have it set as Dual Boot on my system. and I guess this is also not an issue with the laptop LCD itself..
Thanks and I appreciate the help in advance