I solved this problem by updating the driver for the video card, Intel Graphics Media Accelerator 4500 MHD. I googled this and got an updated driver from the Intel site and it worked. The playback then recognized an HDMI connection (when plugged in) and automatically switched the audio to the HDTV. Previously, I only got the picture. I had also updated all the other divers from HP and Intel.
I went from Vista Home Premium 64 bit to Win 7 Home premium 64 bit.