I have my HTPC running win7 home connected to an Onkyo 8 series AVR then to a Mitsubishi DLP. The HTPC video card is Nvidia geforce GT430. If I wake the computer before I turn the TV and AVR on I get no signal. If I power on TV and AVR before I wake up the HTPC no problem. When I am having the no signal problem if I put the HTPC to sleep or logoff or restart then I get the signal. Connections are HTPC HDMI to AVR HDMI to TV.
Is this a handshake problem? How can I force the signal when the HTPC is already running?

Any advice is appreciated.