You mean, if you start a flight at Zurich, the scenery works but, if you land at Zurich after a flight, it crashes ?
First, you should try a flight starting from a default airport, into Zurich, with a default airplane. This is always the first thing to try, to see it if it's the scenery that has a problem.
Also, if you have an addon, like a complex airplane, that takes a lot of memory, it might happen that over the time, you memory has exhausted. FS9, without patching both FS9.EXE and Windows itself, can't allocate more than 2GB of RAM, regardless how much memory you have.
It has been tested that this might be not enough, for complex airplanes flying over complex airports, especially after some time. Have a look at the discussion about the >2GB patch in this forum, it will explain how to patch FS9.EXE and Windows to have FS9 using up to 4GB of RAM. Even if you don't have 4GB, that would be Virtual memory so, it might run slower, but at least it will not crash.
Note, after you patched FS9.EXE for >2GB of RAM, you will need to reinstall the latest Stand-alone Addon Manager or FS9 (latest version, please, found on Zurich web page) to give the installer the chance of installing the correct version, compatible with the patch. But is all discussed in the >2GB patch thread.
