Hi,
I raised a TAC case with this very issue, and it turned out to be a known problem. Here's what the engineer told me to do:
"To Rectify this, go into the auth-proxy table and remove the entry that has the right name (but is associated with the wrong IP address) - move it from the right column to the left column. Then, move the entry with the wrong hostname/correct IP address to the right column in the auth-proxy table. Once this is done you should be able to remove the erroneous entry entirely from the aaa servers entries."
Until we did this the SE wouldn't operate at all - we just got "unknown NAS" error messages.
HTH
Andrew.