I had the same message on one of my R15s last week. It wouldn't go away and it totally messed up the operation of the system. I unplugged and re-booted and everything seemed normal afterwards.
Same as DocJ. I just turned the TV off and forgot about it. Couldn't change channels, view recorded programs or any other function. When I came back to the set later, it was gone.
Doc J....is this a reference to the great one? Dr. J was my favorite player during that era!