Alberta,
I did not correct this specific issue but i have seen this issue in a SharePoint 2010 and InfoPath 2010 form library. After working with Microsoft's support I discovered the problem to be in the xpath of my form. My form was using people pickers and querying the user profile service to pull in email address's of users. Is this your situation? Here is the xpath:
INCORRECT XPATH:
xdXDocument:GetDOM("GetUserProfileByName")/dfs:myFields/dfs:dataFields/tns:GetUserProfileByNameResponse/tns:GetUserProfileByNameResult/tns:PropertyData/tns:Values/tns:ValueData/tns:Value[../../../tns:Name = "WorkEmail"]
As you can see near the end of the statement there is tns:name
The correct version replaced the tns:name with an s0:name
CORRECT
xdXDocument:GetDOM("GetUserProfileByName")/dfs:myFields/dfs:dataFields/s0:GetUserProfileByNameResponse/s0:GetUserProfileByNameResult/s0:PropertyData/s0:Values/s0:ValueData/s0:Value[../../../s0:Name = "WorkEmail"]
Please understand I do not claim to be an XML expert as its a skill im learning in more depth so I cannot speak to the why or what of this error, just how I fixed it.
If someone with more XML and Infopath knowledge would care to educate me I would appreciate it to further my knowledge.
Please let me know if this helps you Alberta and if i can provide any more supporting details please let me know
Good Luck
SharePoint Kev