As a complete novice at Infopath I'm grateful to thoese how have taken the time and trouble in this forum to help me out.
It's not often that I get a chance to provide something in return, but here goes.
I reciently notice some strange behavoir on certain fields, e.g. fields not populating, Formula not running etc, just blank fields.
This problems was present only on fields that I had moved. There were no errors present, but once I went though the process of Re- Binding the fields that I had moved, everything worked ok again.
The moved fields look to be binding to the correct fields, but by re doing the binding fixed my problems.
Just thought that this "tid bit" might be useful to someone (hopefully)