Windows – My display is blank when I turn on the HDTV connected to Media Center

This problem seems to affect many people (as per search engines) with the most suspected/mentioned cause being insufficient drivers from ATI (NVIDIA apparently has updated its drivers for related issues successfully, while ATI tried that too, but some users still seem to have the same issue afterwards).

Consequently you might try to find updated drivers for your video card, but you should probably try the following workaround first to confirm the direction: several users are having success with a little program called hdmiOn. You could try this too by assigning a Windows shortcut key to run hdmiOn.exe whenever you lose the signal.

For more details and/or different solutions you may find e.g. this thread helpful (rather lengthy though), which is addressing a similar issue and resolution experiments.

Update:

With hdmiOn fortunately providing a workaround now, theDude19 seems to be spot on regarding the actual cause being loss of Extended display identification data (EDID), as hdmiOn.exe is exactly enforcing a resend of EDID by simply turning the monitor off and on again.

Given the simplicity of this fix one would indeed think this to be the responsibility of the video driver, however, as usual, the handshake between the involved hard- and software entities might be insufficient on all sides...

I found the solution in a Newegg product review (see the third entry down by Brandon):

Add these lines to the most recent copy of irbus.inf:

[MicrosoftHw]
%USB\VID_045E&PID_006D.DeviceDesc%=IrBus_V2, USB\VID_2304&PID_0225

[ControlFlags]
ExcludeFromSelect=USB\VID_2304&PID_0225

I added those two entries to the irbus.inf file. This gets the Pinnacle Remote kit for Vista to work on XP MCE 2005. Then I checked for a new driver on the USB entry in the Device Manager (it didn't have the device name, something unusual - I forget), and POOF, it installed a new driver and gave the device the correct name (eHome Infrared Receiver).

Now it works correctly. I can change channels from Media Center's guide, and set up a recording from there in one step.