I use WMC for all my entertainment, Media Browser, Music and Live TV.
My HTPC has ah HD6450 with the latest drivers connected to an Onkyo TX-SR875 via HDMI then to my Samsung TV via HDMI and all is control by a Harmony 1100. Anytime I power down my equipment (excluding the HTPC) while I'm in the middle of watching Live TV or Media Browser, the next time I turn it on WMC would freeze and my AVR/TV would not detect a signal until I Alt+Ctrl+Del then I get a signal. I'd then have have to go to Task Manager and end WMC then restart it again.
OTOH in my room, I have a Dell laptop on a docking station connected to a Samsung TV via DVI to HDMI cable and I don't have a problem turning it on and off.
Does anyone have a solution for this?