Had same problem:
- Game crashed and after that the single player galaxy wouldnt start
- Stuck on loading one of my single player galaxies
- Other singe player galaxy worked fine
- Multiplayer worked fine
- mods worked fine
My solution:
1. Go to %appdata%\Avorion\galaxies
2. Make a backup copy of the Galaxy you have a problem with
3. Then go to the copied Galaxy,
4. go to sectors
5. delete the the latest modified sectors
6. start the game and the copied galaxy
7. try removing the latest player.dat files, remove latest serv.dat files etc
I fidgetted with the copy of the galaxy like that for a while and got it to work again..jaay