Aggressive antivirus software often mistakes emulator save states for ransomware behavior because the emulator writes large chunks of binary data quickly.
If a save file exists but has been locked by the system or a cloud sync service, the emulator cannot overwrite it.
If this error only happens with one specific game, the ROM file itself may be corrupted or "locked" by another process. Try loading a different game to see if the error repeats.
"THERE WAS AN UNHANDLED EXCEPTION TRYING TO SAVE YOUR ROM TO DISK."