i connected my vcr to my computer to record some home taped tapes and it worked fine. I then reconnected it to the tv and that's when I found out it won't switch to the required channel to record a program. I try switching to the channel and I get a snowy, noisy picture as tho I disconnected the RF cable from the VCR to TV. it's recording channel 3 ok but not the channel I want. can anyone advise what the problem may be??