I have had a number of occasions recently where I have come back to the PVR to find the 'select HD/SD Pop Up' on the screen. Typically the PVR would be tuned to BBC1 SD (Chan 001).

It would appear that if this has been on screen for some time, 1 hour plus, and possibly when there is no longer the HD programme option available it is not possible to remove the Pop Up using the Red, Green or any other key on the remote. The only way to do this is by power cycling the PVR. Rather awkward if the PVR is recording something at the time.