Not sure if its been posted before but there is a fix from Microsoft for the "Weak TV Signal" error displayed by WMC. It simply raises the threshold to detect a weak signal from 10% (default) to 50% by adding a registry key. The article can be found at the following link:

http://support.microsoft ...

I just found a utility, called HdmiYo, that claims to solve the HDMI handshake problems when resuming from sleep. It sits in the system tray and whenever the computer resumes from sleep it will turn the video off/on which I assume forces another handshake to occur.

I'm trying it out now before I ...