Ah yeah sometime antivirus software is wary of programs from smaller creators like those of us here on itch, maybe it falsely detected a virus in one of Back When's files and quarantined it, making the game unplayable? It might work to redownload and check your antivirus to un-quarantine files from Back When/mark the folder as safe, but after a crash I can understand why you might not want to try that. Sorry I can't be of more help!