I have an older TivoHD which has been having a couple of issues - my live tv picture as well as the recorded shows were showing up pixelated. I had the cable company come out twice to check the signal and swapped a different Tivo in its place to rule out signal strength and the cable company assured me my signal strength was fine plus the different Tivo worked perfectly. In addition I had the cable company change cable cards just in case and that didn't seem to solve the issue. When rebooting the Tivo, half the time it goes to the Power up screen, switches to a black screen that says "no signal" and keeps switching to both - other times when rebooting, it will complete booting up but the picture is still pixelating. I ran the hard drive test 54 - completing the SMART tests as well as the overnight tests and the hard drive passed every time without errors. Could it be that I still need to replace the hard drive or is it another issue?

Thanks.