Ah, that would be it. Norton is notoriously bad when it comes to flagging anything it hasn't seen as a virus. As seen in below links for games by other developers (including notable ones such as Hanako Games and Cheritz) and the Ren'Py engine itself:
http://hanakoforum.nfshost.com/community/viewtopic.php?t=1190
http://dl.cheritz.com/en/questions/view_question/2132
https://lemmasoft.renai.us/forums/viewtopic.php?p=155072#p155072
https://lemmasoft.renai.us/forums/viewtopic.php?f=8&t=38117
https://lemmasoft.renai.us/forums///viewtopic.php?f=13&t=43468
This is the virustotal results of scanning the .exe that is uploaded on itch.io ( you can try it for yourself as well ). only 1 out of 60 antivirus engines flags it as possibly malicious and that's actually remarkably good ( You usually expect at least 2-3 for lesser known files).
Based on your description it seems more likely that it was Norton itself had an error that caused it to hang on checking/quarantining the file than that it was a virus. Forcing the shutdown in the middle of Norton's scan would have been what caused Norton to behave strangely afterwards. My guess is that Norton was able to update/repair itself in those days after. As Norton is the only antivirus that seems to have such an issue with t his game (and this is an isolated case), it may be worth reporting to Norton so they can fix it.
Simply put, the PC would not have recovered had it been a virus (most antivirus software is only good at preventing an infection, not clearing it up. They can isolate files but any damage that is already done, is done. It's like slapping a bandaid on a gunshot wound)