I had the same problem!!! You need to press the set up button which is just to the left and above the menu wheel in the center. Press the + arrow on the menu until you get to C.MODE.AVX Mine was set on AV1. It needs to be set on AV2. Press the + button on the menu wheel to set it to AV2. It now works perfectly. I have no idea how these things work fine and then all of a sudden some little button is off.

I'm so glad I found this site. I was googling the RM U306 to buy a new remote when I found this post. If you have problems email me at dondon@midsouth.rr.com and I'll help you further.