A couple of thoughts (that may or may not be useful
)
1. Many TVs disable the audio outs if the internal speakers are on. Your problem sounds like the opposite; ie the audio outs are enabled and it may have automatically disabled the internal speakers. You could try disconnecting the cables from the audio outs of the TV and then using the TV menu to enable the internal speakers.
2. It's possible that you need to make an additional analog audio connection to the plasma, even though you are using the hdmi connection which is capable of carrying both audio and video. I know it sounds counter-intuitive, but I just read the manual for the Sony LCD I am considering and it says you must hookup the L/R analog audio connections when using HDMI. Maybe there is no path to the DACS when using the HDMI connection so it requires the additional analog audio connection. Check the Plasma manual and see if something similar is going on there.
