Not even Chris Evens has figured out all the do's and don't when he release's a aircraft he claims works in V4. Understanding that, you must allow for these bugs to get worked out, one by one. Some aircraft will work while others do not, it is that simple. Uninstall any that do not work and are causing crashes. Wait a little, read forums, and watch for those who dedicate their lives to freeware, get the bugs fixed. Most of these errors are in the changes in code that turn P3D from 32 bit to 64. In the end it will be well worth it. Sure beats FSW... Scenery files seem to all work in P3D v4 . I was able to download all my photo scenery. That is due to scenery files are nothing more than textures while aircraft are far more involved in operation and formulas.