Hi, Rexster63,
It might be a corrupt preference causing the issue, or the issue could be confined to just that one project.
First try deleting preferences. To do that open iMovie while holding down the Option and Command keys and select to delete preferences in the box that appears. iMovie will open in a new library. Reopen your old library to get back to your projects. Now see if you can share out your complete project.
If still no luck, try creating a new project. The go back to the original project and do an Edit/Select All, Edit/Copy, of the media in it. Then Edit/Paste the media into the newly created project. See if you can share out successfully from the new project.
-- Rich