After a couple of minutes, mine used to turn off my zone 1 speakers when I had zone 1 and 2 on at the same time. It's apparently a handshake issue but easily fixed. I had to run an optical cable from the receiver to the player in addition to the HDMI cable and that solved the problem. There may be another difference between your set-up and mine, though. I'm using the "Zone 2 line out" with a separate amplifier rather than the powered zone 2 outputs. I've had no problem with my zone 2 cutting out.
i have an onkyo 605 receiver which when in zone 2 shuts off if volume is turned up 2 high. any suggestions