Firmware avr-e400 problem firmware

Your problem could be a bad dsp processor which is on the hdmi pcb, change that pcb and the problem should quit

Use factory reset procedure, if that don't work you may have a bad main control relay or the relay control transistor may be bad

If the DENON has an HDMI output, and your TV has an HDMI input, then use a HDMI cable. Then, use the TV's remote-control to select "source" (or "input") as 'HDMI 2' or 'HDMI 3' (assuming that you have been using 'HDMI 1' to watch TV).

Personally I would use an RCA cable and hook up the AVR.
((RCA out of TV to AVR audio in))
((cable box HDMI cable output to TV HDMI Input1))
(As far as the AppleTv I would use a separate HDMI Input2)
If your AVR has a dvd or blue ray player Hook up a
HDMI cable out to another Input HDMI3 of the TV
using separate inputs on the tv will allow your surround system to be
used on all modes(CABLE,DVD/BLUERAY,APPLETV)

If you have done a Denon reset and you still get the same thing, the hdmi/network pcb which is on the same board as the hdmi is defective.

Ask the manufacturer:

usa.denon.com/.../ProductDetail.aspx

do you have it in surround mode?

You have a software glitch the processor board needs changed.

AVR-E400 has an RCA subwoofer output. This is a line level signal that must be connected to an ACTIVE subwoffer (has its own power amplifier) Also the source must contain subwoffer signal (5.1, 7.1, 9.1 surround sound etc) You will not get subwoffer signal from a stereo source such as audio CD, non-dolby type TV etc. Cheers, Don.