Thanks for the quick response. We thought we were going crazy...
The work around we found was to add a blank section at the end that is not restricted. The user can click into that 'section' and the Find feature is again available. It allows you do the search, but will not allow the user to 'click' forward through the
found items. However, the items are highlighted throughout the document and the user can scroll through, see the highlights, and review the associated text. Not ideal, but certainly doable. Thank you!
I don't have an answer as to why you are having this problem, but for what it's worth, I use Word 2010 and I took several documents (docx and doc extensions) and restricted their formatting and editing. I did not add a blank section at the end. I was able
to search through the document, including clicking forward, with no problems. I also created a short form and restricted the formatting and editing and had the same results. One of my settings must be different than yours, but I can't imagine which.