Is seems when opening pla AC file and selecting "Read elements directly from archive" crashes all other open AC files. @GRAPHISOFT , needs checking.
You need to send the bug report off adding a description about what happened.
Take note of the Bug ID number and then contact your local Archicad support and give then the number as a reference for them to look into.
They should then look into it and if need be get in touch with Graphisoft HQ.
They should be able to get back to you with hopefully a solution to the problem.
If it does not create a bug report then you still need to contact your local support.
They may need the files causing the problem to look into it.
It may be specific to your files - no-one else seems to be having this problem, so it is probably not something anyone else can replicate to look into it.