I've been using a code set almost identical to the first one you list on all my HR20s. But with the latest use of the "exit" button, I have been having the same issue you posted, only with my HR24-500. The only way I could solve it was to adjust the "duration" setting, I have it at 0.23 seconds and so far (after three days) I haven't seen the problem, but I'll give it a while longer and post back.