Tobias,
Thank you for that info. The real question is this. Most of the users have been assigned to Index Profiles to provide very granular control over who can see and modify certain documents. 'Add New Entries' is not an option in an Index Profile, so insufficient rights errors occur during workflows for these users. It seems that a Custom Profile must be created, the 'Add New Entries' permission given, and then this profile assigned to the users along with the index profiles. And that this is by design. Have I got that right?
Thanks again,