From "The Bug Report," Infoworld Dec 15, 1997

"If you change the server key of a Banyan StreetTalk server, the rest
of the network may not be able to see this server for as long as 96 hours.
Banyan says the reason is that StreetTalk needs as long as 96 hours to 
age out a StreetTalk instance.  Before that, the previous association 
with the original server key is still in the network, causing confusion (!).
Banyan has two workarounds:  take the server off the Net for more than
four days before reattaching the server with the new key, or schedule a
"Forget Group" dial-in to be done by Banyan Support.  Banyan also says
that the Forget Group dial-in needs to be done on any 5.5X server other
than the problem server."