Alright. If you do lose your saves/they become incompatible, I give players the ability to jump to whichever act they want to play from, when making a new game.
It's hard to say what's causing your issue, but if you've deleted the games folder from %appdata% and your device still has issues, then the problem might be a memory issue(Maybe Ram).
Try task manager and make sure nothing is taking up memory.
You could try playing renpy games on another another device
(Most renpy games usually have an android port, so you could play on android/phone too.)