PDF form can only be filled out once?!

Hi everyone,

For years, I've been using the form tools within Acrobat Pro to create PDF forms for my users who only have Adobe Reader. All in all this has worked well but recently, I've started getting complaints from them that they can only fill out a form once and can't change the contents of the text fields after the PDF has been saved and closed. To be clear...

1. Open the form for the first time.
2. Populate form fields with information.
3. Save and close the PDF.
4. Re-open the PDF just saved. Although the fields are still populated, the user can no longer change the text within the form fields.
5. A message appears indicating that, "This document enabled extended features in Adobe Acrobat Reader. The document has been changed since it was last created and use of extended features is no longer available....."

This may seem like a dumb question, but is this...really...expected behavior? If so, here's the kicker. If I open the saved PDF form in a web browser, the text within the fields CAN be changed and saved again.

If this is NOT expected behavior, how do I make a PDF form so that it can filled out and subsequently changed later as many times as needed (purchasing additional licenses of Acrobat Pro for my users is not an option)?

Thank you,
hp