We see this as well. MSRDC.EXE processes need to be closed in order to have users login properly.
I have seen it on new but also 2 month old releases of the client.
I would almost dare to point (or am I already? :)) to the monthly updates of August.
Since the cumulative updates we've been experiencing this AND also other issues like users who connect their laptops to monitor/kb/mouse docking hubs experiencing USB errors forcing them to shut down and restart in order for it to work again.
Something's messed up. Hope it'll be fixed sooner than the multi-monitor bug the client had over a year ago, because that took months.