I just had the same thing happen to me last night.....startling and scary. I am also having multiple no sound issues....only had my 970 for a few weeks. Have a call into support....may be sending it back even though it sounds great when it works right. I just seems very unstable to me, especially after suppossedly having the new firmware.
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B&W 804s mains
B&W HTM4 Center
Outlaw 990
Anthem MCA 30 AMP
Audiosource Stereo AMP
Monitor Radius 180 surround
Comcast DVR
Sony HX929 LED TV
Apple Air Express/Apple TV