Help! My chain and rear cogs are getting rusty. This sucks.

Is this normal if you ride in the rain? Should I be drying off the bike after a wet ride??

Crap, is this happening because I used paint thinner to clean it a few times? I use Simple Green now, but before I knew bettter I used the thinner a few times.

Could it be from riding on salted roads? There's been salt on the roads for the past couple of weeks.

Is there a way to fix it now, or should I just wait until after the winter and then replace the stuff?