I had a similar thing happening and it was caused by a method in another control that was triggered by a refresh. Try turning your event tracking on and set a breakpoint on the value in the controlsource. This should help you pinpoint the code that is causeing the control to revert to the original value. On my form it was a controlling grid that caused a locate in the controlsource file. Since the grid was designed to locate records I disabled it once the user started editing and the odd behavior stopped. Hope this helps.