I start the launcher, enable my mods (no, it's not a mod incompatibility issue), and start the game. I see a black screen for a few seconds, then it crashes. Both the game itself and Steam. I tried deleting config.xml, and it worked at first. Now it doesn't.
Hmm, try deleting the whole folder containing the config.xml? And verify file integrity through Steam?
I don't really have anything else to suggest - the game did work for you in the past, right? We haven't pushed an update since, I don't think. Try reinstalling?