The sound is perfect for a minute or two then it sudenly goes Mute. it may come back on between 3 and 40 minutes later. The problem is the receiver not the earphones ( I've tried several.)

Check fuel pressure at the injector rail. Could be pump is failing or filter is clogged.

It might be over heating? do you have the right ohm speakers hooked up should use 8 ohm speakers as lower ohm speakers will cause this problem!

Rice Crispies? We hope not. You may also want to check your connections for security. Switch out your audio cable (s) to rule that out. If that does not correct the issue and your settings are standard, you may need service. ^CL

Here is the link you may visit for service assistance:

http://www.lg.com/us/support/repair-service/find-repair-provider

Your Lamp needs to be replaced.
Mats Electronics 1-800-628-1118 they have Lamps for $89.95

check ALL the ground leads coming out of the battery,sounds like somethind is loose or not making a perfect connection,get back to me and we'll go through tracing the problem. remember lights do not need a pefect ground Thanks Ray please rate my fix

Is it ok when you watch regular TV thru the cable or sat?

is the check engine light on,if yes scan codes,it will point you to problem area

I don't know if this will solve your problem, but I have a question.  Does the receiver sit under another piece of hardware?  Especially one that gives off a lot of heat?  It is possible that the amp or power supply is overheating.  The heat forces the receiver off until it has a chance to cool down.  Then when it turns back on, it starts to generate heat again.  Try moving it out from under any other gear or out from under a shelf so that lots of air can get in the top.  Maybe even try putting a fan over it, just as a test to see if this helps.  I work at a recording studio in Toronto, and we were having the same problem with one of our digital multitrack tape machines (No the studio is not trapped 10 years in the past - we just use tape for backing up and client delivery).  Anyway, early in the day, the unit worked fine.  If we tried to use it later in the day, we would get glitches all over the tape, or the transport would freeze up altogether.  We found that when we moved the unit into a rack where it could really breath, and where it wasn't right under an 8 channel mic pre-amp, that it worked without any problem.  I hope this helps.  Good Luck!

Protection circuit fault kicks in. No vertical Deflection (V STOP),B+ over voltage protection (OVP), This is about a $150 -$200 to fix.