I've not run into any problems such as you describe Hans but that is because I kept my old FS9 computer, which is operating on a Win 7-32 bit platform, for the expressed purpose of doing scenery work. All of my tools are there so they continue to work in their native environment. I have it networked to my primary computer so jobs like you described are done on the old computer and then transferred back seamlessly. Plus I keep a complete mirror backup of my FS9 set up on the old computer. Useless for flying in FS9 but still works great for development work. One of the airports you noted is a scenery I contributed to. All the work was done on that old computer including texture conversions. Just thought I'd mention this in case it is an option for you because it would avoid trying to pound round pegs into square holes when adapting old tools new operating systems.