Note: When using Ozmoo on C64: If you save the game using one Ozmoo build, and try to restore that save using a different Ozmoo build, you can expect it to either work perfectly OR crash the game - it depends on the code size of the two builds. The more features you enable, which weren't enabled in the original build, the less likely it gets that you can restore an old game save.
If you still have problems, please file an issue at https://github.com/johanberntsson/ozmoo and we'll have a look.