IP07 supports features and XSL constructs not available to IP03. I'm assuming that you exported your 07 form template to 03 so that you could develop in 03.
The "protected" bit is a little-known feature that InfoPath supports which allows you to design your own custom XSL views outside of the designer and have them used in the form template. There is an attribute on the xsf:view element in the manifest.xsf file which determines whether a view falls into this protected category. The attribute is designMode="protected".
If you remove this attribute from the xsf:view element, you will be able to open the view in the designer. However, if there are unsupported constructs or features, those will be lost when you make changes to that view. So make a backup copy of your form template before attempting the attribute removal.