Setting Preferences--Structured Authoring cause FM11 to crash

Hello,

I changed Preferences setting to Structured Authoring.  I was prompted to restart FrameMaker 11.x.

When I tried to open a file, I got this error message:

Any suggestions on what I might have done wrong?  If there is a bug or workaround for this, I would love to find it.  Thanks!  Laura Ferrer