Hi, Annhamm,
Yes. It can be fixed. You do that by redownloading iMovie. To
update/redownload iMovie 10, drag your iMovie 10 app from the Applications
folder into the trash, but do not empty the trash. Sign in to the app
store and open your purchases folder by clicking on your name at the bottom of
the app store side bar. You will see your purchases displayed, including iMovie
10. Redownload/update iMovie from there. If not successful, drag your present
iMovie app out of the trash and return it to the Applications folder.
The above procedure should solve the insufficient disk space issue.
-- Rich