I haven't heard of anyone running into this, I don't think. The cable box is effectively resetting itself? I'd probably start by getting some input from Harmony's tech support - their software somewhat limits what the user can do, but their techs can dig right into the nitty-gritty and may be able to find what command is resetting the cable box. I'd suggest testing the interaction of the original signals themselves (using the cable box and 990 remotes to re-create the start-up sequence), but I really think that's overkill. Most likely there's something out-of-place in the "Watch TV" activity macro.