In one user mailbox anything sent from any distribution list in our domain shows up as being from 'System Administrator'.
It only happens when they are viewing the inbox using outlook (OWA is not affected), and its persisted across computers (though it did not happen immediately). When other users view the inbox from their outlook install (ie open users folder), everything appears as normal.
Other folders are not affected. if a message is moved into a subfolder, the sender displays properly.
Because of the persistence, and it only affecting one user, I suspect some user behavior is causing this, but i cannot determine what. Ive checked the contact list, and its not that.