Designer crashes when opening form

We have a form that was created with Designer, but I am no longer able to open it for editing. When I try, I get the error that LiveCycle Designer has stopped working. The last time I needed to update the form was about two years ago, which I was able to do without any issues. The form still opens and works fine in Acrobat, but I need to make a couple of changes to it now.

I'm using LC Designer ES4 (11.0.0.201303031.892433), and I'm able to edit other forms without any problems.

The form is at http://www.sussexcountyde.gov/sites/default/files/PDFs/Employment_application.pdf, if someone else could see if they also have the same issue when trying to open it in Designer?

Thanks for any suggestions!!!

Debbie