Because of this message, I also can no longer save the forms created into PDF.
Is it the case that you have exceeded the trail time period for Acrobat XI? How long ago did you install the trial and when did it stop working? Were you strictly working with your files locally or had you uploaded them to the Formscentral service?
I installed Acrobat XI about 10 days ago. So, I should still have 11 days to go.
It stopped working yesterday.
I have both, one form uploaded to the Formscentral service ; and about 5 forms on the local drive.
The forms on the local drive are the most important that I want to be able to retrieve.