Weird happening

My HR21-700 just did a very strange thing. I was checking the signal strength on 99s to compare it with the reading I had just gotten on my H20-100 for 99b. While the signals were loading for 99c, it got to tp 11 and then gave me zeros thru 14. Then starting at 1 they all went down to zero. I checked other satellites and was getting the same thing. I got out of menu and was getting the dreaded 771 on every station. I went to check the H20 and it was operating normally. After I did a "red button" reset everything was back to normal. This makes me very nervous now. This is the first bit of trouble I have experienced with this unit.