I have a 47" Mitsubishi LED TV and my cable provider is with Charter DVR. Each time I power up both Tv and Cable box I have to wait about 10 minutes before I can change the channel unless I am standing directly in front of the set. It's like it has to warm up before I can change the channel. A real pain in the derirer. I am sitting about 8 feet from set. Is this normal? The remote is the cable box one and it has new batteries in it.