This has happened before and just gone away, but out of the blue realview is turned on and the tab is greyed out. Happens in assys only. I do not think the usual driver update remedy is the answer because it happens and may go away for months. Is there a setting somewhere that gets turned on? I know I have not reset any settings, knowingly. All my assys are small and about the same size so it isnt an issue with file size. Also it is not particular to one assy, when it happens some assys are fine and the realview tab works others just seem to have a lock on the tab.