You are amazing! The space center screen became unusable. I couldn't launch a flight, enter the Tracking center, VAB, or SPH. If I tried to exit the save through the ESC menu, nothing would happen. Couldn't even use Wack a Kerbal from the debug menu. I started clearing out Mods. When that didn't work i began looking through sub assemblies and saved crafts for corrupted files. Turns out that by forgetting to revert a flight where poor Corcal Kerman died, lead to this hard to find bug.