We had a widespread issue that was similar to this about 5 weeks ago. The solution was to first power-cycle the XB6 modem and then (after the status light turns solid white) power-cycle each set-top-box.
Although a box can sometimes fail, it's almost impossible to have 2 or more box failures, much less 4-5. This indicates to me that you have another issue. It's almost always related to signal problems at your home or in your neighbourhood. This was proven time and again with digital cable and is being repeated on IgniteTV.
Although a new box sometimes seems to solve a problem, most people find that the problem will return shortly because the problem was not the box. With many IgniteTV installations utilizing WiFi, that brings another parameter (poor WiFi, or WiFi interference from say neighbours or whatever connection you have between the various boxes) into play. So that needs to be checked properly also.
