I get an error when trying to save a copy of a corporate document to My Favorites folder ("Error - you do not have the rights to save in this folder or to edit categories. If you require these rights, see your Business Objects Administrator").
This behavior is by design, since end-users don't have Edit rights on the categories themselves.
As a workaround, when doing the 'Save As' operation, click on the Categories tab in the Save As window, expand Corporate Categories, and click to uncheck all of the boxes for categories that have been selected.
See also How to Copy a Repository/Corporate Report for Editing (PDF).