Hi Chris,
That's a strange error. I would first try to reinject the XSN to see if that corrects the issue.
Our full list of qRules documentation is here. I think these three docs might be interesting to you:
http://www.infopathdev.com/files/folders/qrules/entry61475.aspx
http://www.infopathdev.com/files/folders/qrules/entry49216.aspx
http://www.infopathdev.com/blogs/hilary/archive/2009/11/16/submit-items-to-a-sharepoint-list-with-qrules-v2-0.aspx
Let us know if you have any other questions!