You need to check that the switch box has all the cables plugged into the back securely, they have a tendency to come loose. That would explain the flickering. Also, you need to make sure that the Bedroom TV was wired properly, as it previously was using the composite (non-HD wiring). You should not need a signal booster, as the switch box is amplified, as I recall.
You should have this switch box, or one very similar: AVS100HD
I think I have the AVS200HD, which is similar. If you have that one, you can get the data sheet from this page: Documents
What are the signal strengths on the three satellites you are getting? Should be 99, 101, and 103, if you have the latest Trav'ler. Don't worry about the "S" numbers, just the "C" numbers for each sat.