cisco explorer 8642HDC multiple issues

2 months ago I got a new box because I lost 70% of my recordings, now especially after losing our cable service in our area for 2 hrs. last Friday night, I have had a lot of issues with my box upstairs. 1st I have reset & unplugged it but the problems still come back. I don't know how many times I have to reset the thing. There has been a lot of tiling and quick blank screens, audio dropouts, 1 time I got the 1 min. recording where the show starts and a sec. later for a min. there is a blank screen on FOX. also this week my manual recordings I set, I noticed the times changed from 2 hrs. to 30 min. for ex. I catched it before they recorded. Also when the tiling happened 1 recording stopped recording in the middle of the show. My other 2 boxes work fine with not much tiling. The cable from the garage plugs right into the box. Maybe the signal strength is a problem going from the amplifier to my box. Or maybe the amplifier is old. At times I have had other & some of the same issues before.