P.S.
Hi Groovin_DC-10.
Have had issues with older add-on planes (Fsd , Flight1 etc) in Win7 32bit.
Folder permissions allowing control of the Fs9 location and the Installing from location are mentioned in a lot of online advice.
Also always running the FS9 default flight (Cessena 172, Seattle, active runway), has been helpful in my efforts.
Good luck with your great PSS planes.
rolan_tuck.