Thanks Jimmy, unfortunatley I have deleted this saved the document and tried re-opening it in infopath but it will still not allow me to open design mode, it gives me this error:
The form definition (.xsf) file contains elements, attributes, or structures that are not valid.
Error details:
The keyref 'RAGStatuses_298' does not resolve to a key for the Identity Constraint '{http://schemas.microsoft.com/office/infopath/2003/solutionDefinition}xmlToEdit_name_key'.
Line 153, Position 5
</xsf:view>