737-800 Liveries

Hi Guys, have just recently upgraded to Vista and it has taken sometime to get things back to where they were. Have re-installed the 737-800/900 and downloaded several liveries from the PMDG website. The -900s are fine but I cannot get the -800s to load. They install fine and the files are there in the FS9 Aircraft files but when I run FS9 the program cannot find them.Also, I cannot get the airstairs to work on either model. I am aware of how you set the keys to perform this function but it wont work.Any assistance would be appreciated.John Watt