Mark I made as you suggested, unistalled, reinstalled and repair. Nothing change. I tried tomsave a cold and dark state via cessna 172 default and change to 757, but nothing change.

Is there a way to completely uninstall it?
I mean completely.I want that installer ask me for my serial key, and now when I reinstall it doesn't ask me for. I suppose that installation is corrupted and even if I uninstal/install nothing change,

I have to start from scrtach, any help?