Hi Mel,
I have checked the system logs and nothing seems strange. I have compared the entries between this form and another that was created directly in 2010, and the log entries are very similar
When I copied this form from the 2007 version, I was accessing a different domain. So some of my data connections were actually not correct.
When I published my form, I published it to a library called "Lead". I have deleted this library on a number of occassions, so obviously there was often a version in the recycle bin.
When I noticed this publishing log entry problem, I published it to a library called "Leads". I have now tried multiple publishes and NO error.
This does not really make sense, but now it works, so go figure. I will mark this as the correct solution, after I hear back from you.
Regards.