Infopath form errors on file attachments

I have several processes that require an Infopath form to have an attachment. On the completion of the process the final view, with all fields locked, is loaded to a form library. I have many users that get an "invalid xml" error and/or an "xml tag not closed" error that relates to the file attachment field. Other users can open the form without any problems.

Has anybody seen this? Have any suggestions on how to fix it?

Thanks,

JR