Things which may have helped me, I'm not sure what, because I did these all pretty much simultaneously, and I've had this issue or a similar issue since Warband first came out, before any custom module play:
Changed my graphic card settings.
Turned off textures on demand/forced single threading.
Switched to Dx7.
Always play in windowed mode.
I haven't had any freezing/crashing issues with Mount and Blade or cRPG since I've made these small changes, personally.