It's clock stretching. I've run into it many times with Sony equipment, especially BDPs. Sony likes to dance to their own drummer.

I think it is all attributed to IC2 bus where Sony (Display, AVR) likes to use their own clock speed while the master (matrix switch of your choice) does not agree.

For a good explanation that I can't put into better words:

Clock stretching is a phenomenon where the I2C slave pulls the SCL line low on the 9th clock of every I2C data transfer (before the ACK stage). The clock is pulled low when the CPU is processing the I2C interrupt to evaluate either the address or process a data received from Master or to prepare the next data when Master is reading from the slave.

The time the clock is pull low depends on the time the CPU takes to process the interrupt and hence is dependent on the CPU speed and not the I2C clock speed.

Credit go to this sight for the explanation.
[Link: robot-electronics.co.uk]