Today we were trying to merge two fixture libraries together. When we re-opened the show file, using the "Fixture" button causes the program to crash. The strange thing is that even backup files from before the merge cause the same problem. This is also the only button that causes the problem. I'm attaching the show file if anyone wants to try on their machine. We have tried a few different systems here with the same result.
Are you trying to merge ALL the fixtures from one library into another? This can cause a problem as it will fill the library and not allow all fixtures to be merged. Once you fill the library, your merged fill can not accept any further libraries and you can not remove any libraries to create more space.
I suggest that you merge only the fixtures you need and not all fixtures...