asterisk users - Sep 2005 - SNOM 190 '486/Busy here' after upgrade to firmwa re 3.60s

I have a Snom 190 that refuses to accept calls after upgrade to firmware
3.60s, latest. I get "SIP 486/Busy Here". No change in the dialplan,
nor
settings in the phone. Calls out fine. I did 30 other phones yesterday with
3.60s with no problem, this is the only one. In the phone's log I get:

[5]22/9/2005 17:01:00: timeout::callback: Registering with timeout of 0 ms
[5]22/9/2005 17:05:45: Match challenge for user=9002, realm=asterisk
[2]22/9/2005 17:07:31: Denying call id=-4 reason=unconditional <--wtf does
this mean?
[5]22/9/2005 17:07:31: Dialog -4/2 going to terminated
[5]22/9/2005 17:07:31: timeout::callback: Registering with timeout of 0 ms

Any Snom factory guys on the list care to comment?