cyrus21: Address family not supported by protocol

[Erik Steffl <steffl@bigfoot.com>]

  got the following error message from cyrus after reboot:

Sep 13 03:06:40 jojda cyrus/master[9483]: unable to create imaps 
listener socket: Address family not supported by protocol

  and cyrus imapd does not listen on 993 (MUAs cannot connect to it). 
It was working fine before reboot. Other than not being able to listen 
cyrus seems to be working, the emails are received and stored as usual.

  system:
    debian unstable
    kernel 2.6.11
    cyrus21-admin 2.1.18-1
    cyrus21-clients 2.1.18-1
    cyrus21-common 2.1.18-1
    cyrus21-docs 2.1.12-2
    cyrus21-imapd 2.1.18-1
    shorewall 2.4.3-2 (is this relevant?)

  any ideas what this means? google didn't find any answers (found same 
Qs), didn't find any relevant bugs either.

  TIA

	erik