Wondering if anyone else had encountered this. When I attempted to create a Media ID Generation rule on my 2008 R2 media server, it threw an error "Failed opening tmp output file (86).  The troubleshooting guide suggested to look at the security on the vm.conf file.  Security was fine, so I tried "Run as Administrator" option when opening the NBU console, and was able to create the rule.  The account i was using is an administrator on the server.  Disabling UAC also let me create the rule.