it's been a few days now and the screeching/loud volume hasn't happened since, although i expect it anytime.. i do have other directv dvr receivers and a cable tv input to test on it if it happens again though. this happened right at the start point when powering up, so maybe the handshake between the hd receiver triggered it...if it were the directv rcvr. to share the entire set up i have monoprice 4x2 matrix switcher/splitter fed like this: hd rcvr 1(active when the event happened), hd dvr 2, computer 3, and hd hdvr 4. the sharp is on output A and i have a panasonic lc-32s1 on output B. I did check the panasonic (output B with input 1) to see if it was the HD rcvr 1 and the audio was fine while the sharp was screeching, i didn't switch to any other inputs to check the audio.
here's another tidbit that happens along the way. i generally power up each set individually but when i turn the sharp off the via remote or side power button the panasonic shuts down too. i tried this in reverse and it doesn't work .. kinda wierd. anyhow i just got an email from sharp to extend my warranty for 1 or 3 years, and being a victim of a dell 3201c that stopped working just out of warranty that can't be repaired resonably i think i'll bite on the sharp offer.
thanks for listening i'll post if it happens again.