Hi, William
Weve just started using promethean boards at my school, what I have found is that if you have used curved lines in your smart notebooks then it will crash activinspire, if you change the curved lines for a shape drawn using the "shape recognition pen" which will give the same effect except for the arrow at the end, then save and try to import again it should be successfully imported.
if you could let me know how you get on,
Ive sent a support request with my findings to promethean so hopefully this will be resolved with a future update.