How do you do it? Is it something I might be able to use?

We capture security data related to databases (db servers) we administer, as to who connects, what access they have, etc. We have an SSIS package, that connects to all servers and pulls the data daily. (Some similar scripts I think are available online too, to get database level permissions and server level permissions.) This is stored in our database and made available via reports too.

Well, the name IS correct, and the user CAN log in to the database. Can you think of anything else I might try?

1)

Well, doubtful on this one since you can retrieve data for one user atleast, but can you please check this link?

http://blog.matticus.net/2009/08/windows-2008-and-xplogininfo.html

2) Is there any error in SQL error log when this xp errors? If there is, I was wondering what the login error state number is?

Thats all I can think of right now.