Local SD channels freeze in the morning

[#1]

For about a month or so (about the same time as 1.9 update) all SD local broadcast channels will freeze at the same time on all SD & HD boxes. (4,5,6,7,9,13 . . . . )The HD versions of these same channels never have this problem. It happens most every morning about 3-5 times.

 After about 20-30 seconds either;

1. The channel will change to another random local channel by itself.

2. The channel is not available message will appear.

This is also a problem at a co-workers house in Vienna, VA. (I'm in Arlington) We both have just gotten new boxes this week & still having the same issue. Signal strength is not the issue. I can't believe we are the only 2 people having this issue.

Any ideas?????

Thx!!

[#2]

FWIW, this happens only in the morning & affects only local broadcast channels.