Are we talking about clock drift? I truly hope we aren't. Most comm devices behave poorly with crystals so far off that you notice more than a few seconds of clock drift over a day. I'd hope that the clock is updated at least that frequently. I think we are rather talking about some uncertainty in when the updated system time is written to the HR20's real-time clock. Clearly an update does happen, or some devices would get many minutes off. Hard to debug from the outside, but since this wasn't an issue with the HR10 (or at least not with MY HR10), I'd put the blame on software latencies in the HR20.