It could be that my TV is opposite a window but I notice the unresponsiveness even when the blinds are closed and at night. There is no direct line from any part of my TV to the front of the Nextbox so it couldn't be the TV.
Please re-read the link I provided on IR (infrared) interference. It has nothing to do with visible light. I'm not saying definitely it's the cause, however IR spray from various devices, including TVs, that are not set up properly, can affect how well remote control signals work.
We're just trying to figure out why your remote control doesn't work properly. Do you have another one? I also use rechargeable batteries, but perhaps you could try a regular set just as a test? One thing you could try is turning off the TV, leave it off for a few minutes and then change channels on the box to see if the responsiveness is any different viewing the front of the box. (You will have to select display channel on the box for this test).