@RockmanForte: I was joking

Actually I think he wasn't using the wifi... the scene he described is obtained when you choose the first option and not the second one (which means literally "Communication").
@gadi800: Anyway, I made a more deep testing. It seems that even though the correct save type is EEPROM 64 KB, the cause of the crash is not the save type but the emulator speed. In a nutshell, the higher the emulation speed, the less likely the emulator will crash. If you have set the speed at realtime or less, then the game crashes almost always. If you set something higher (for example Unlimited MHz 10%, Disaster), then the emulator doesn't crash that often. And this is valid whether the save type (of course a wrong save type will prevent the game from saving correctly).
So the solution to the problem is:
- open your game
- go to Option->Emulation Setup
- choose a high speed (Unlimited MHz 10%, Disaster would be the best)
- choose also EEPROM 64 KB as your save type
- click on 'OK' and go to File->Reset
Just a note of precaution. what I said above is just the results of empirical testing and the "real theoretical" cause may be something else. It just seems to work with what I suggest above. There may be other better solutions that will work for sure but for now, all I get is that.
Good luck.