Might sound daft but is your power lead securely pushed home into the socket, I have a friend with an Optoma PJ who was having similar problems & it turned out to be this issue.
is it def power loss?
I have a 5910 awaiting collection for warranty with similar issues. looses picture and seems like its dropped power but I don't think its that.
so whats loosing power? your projector? is it somewhere that you can see if the power lights go off?
I have an Epson 5900 with similar issues. Epson have had me connect to amp and direct to bdp with same results. it seems to be dropping ac power but it isn't.
do you have a long run hdmi? it could be that. not strong enough signal, pj goes blank and no sound from avr.
the projector loses connection from the yamaha avreciever because the smart tv trips the the yamaha so both projector and yamaha lose connection at once then both restart seconds later i cured it by not having a hdmi connection between the yamaha and tv