Only other time I saw this was when I'd moved my incomplete folder to another place,and or not copied folder completely,but this is rare, i also got this message when I had two incomplete folders !
I think ukbob has the right answer.Why did you title your query''Upgrade''? My troubles with that problem started when I was installing new hard discs.
N2

__________________
''Kindness is the hardest thing to give away,it keeps coming back''