asterisk users - May 2003 - Strange SIP registry behavior

I have several users I register for in sip.conf.  They are all on
the same host, and normally everything works.

However, once in a while (seemingly at random) the IP address it
is sending the registrations to changes.

register => 3557*752@somehost/*3557*752

is what I have.  somehost always resolves to the same IP address, but
now when I do a "sip show registry" it lists the IP address of one of
my SIP phones.

I suspect memory corruption, but haven't had the time to track it down
yet.

--Michael