ship explodes on launchpad

[MoonPies]

having an issue on the launch pad. as soon as the staging light turns green, the ship breaks apart and launches. i have mechjeb, interstellar extended, real scale boosters, modular rocket system and kerbodyne plus added on. any thoughts?

[MoonPies]

did some messing around, narrowed it down to the mechjeb2 capsule. i even put it by itself on the launchpad and it exploded and launched itself sideways at the same time. everything else works fine.