This seems to be related to https://bugzilla.samba.org/show_bug.cgi?id=2509 Example 1 seems to have been fixed, however example 2 continues to pose a problem. The error message using User Manager for Domains for Win2k3 server on an XP workstation reads: "The following error occurred changing the properties of the global group Test The user name could not be found". This appears to be intermittent - about 5% of the time it works as expected. The rest of the time it doesn't.
Created attachment 1719 [details] Level 10 log taken while the issue was recreated.
This is working well in the current tree for me. Marking as fixed for 3.0.23.