I believe this was an issue in 7.0 that was corrected in 7.0.1. The release notes show:
"Downloading workbooks from a version 7.0 server could fail with error "You don't have permission to access <workbook> on this server" or "An error occurred when loading from the Tableau Server". This would occur on systems using Active Directory (AD) with either a large number of security groups or groups that spanned multiple AD domains. This problem has been corrected." (http://www.tableausoftware.com/support/releases)
Try upgrading to the most recent version of Tableau from your Customer Center at
If this does not resolve the issue, I noted that you sent in a support request as well, and someone will follow up with you.
Hope this helps!
That did the trick - thanks.