The game saves a config file in your Documents/Dipets/config.txt. Maybe it saved a wrong config for some reason and that's why the resolution is wrong... try to delete it and start the game again, it should generate a new one (I'm still investigating what could be happening).
I see. So the method I'm using to get the screen size is not working properly in your case. I will change that method with another one that can probably solve the resolution problem. I'm not sure if that can help with the FPS problem...
I am still working a bit on some of the other problems I found so I will probably have everything done by the end of the next week (around friday).