Have you tried power-off reboots? With my Wally and Playmaker, what I've found out the hard way, is that if I do a re-scan after I get the "blockage" screen, I continue to get them, even if I've moved the antenna to a supposedly better spot. If I actually power off the receiver (10 or 20 seconds before plugging back in) I get a normal switch scan and search and it's usually successful. Likewise, I've found that with my Hopper, USB issues (especially with my OTA tuner) are usually cleared up by a power off re-boot.