Oh dear - not a lot of help either, but I have successfully installed V7 over version 6 on all computers I have an interest in. Two run on XP pro with SP2, one on XP home with SP2 and my trusty lappy on Win98 series 2. In every instance, the downloaded file recognised an existing registered version of V6, deleted it and installed itself seamlessly. Thinks - have you downloaded a corrupted file from Grisoft?
P.P.