mitsubishi WS65909 error code 23

First let me say this is a great site, had green blinking light of death about a year ago and this site walked me through it and all was well until now. My problem is set works great for days then just turns off. Run the LED diag. and get code 23. If I let the set sit awhile 10-15 min. all works good for days until it just turns off again. Maybe a day or sometimes weeks.  Have a electronics background and have downloaded all manuals and dvm ready to go, just need some help on where to start and what to test for.  Any help would be much appreciated.  [email protected]