asterisk users - Jan 2006 - Errors with bristuff-0.3.0-PRE-1e and asterisk cores

Hi,

can  anybody tell me what the errors mean and why my asterisk server falls from 
time to time. From time to time means several hours, not regularly.

I also can provide a core if someone can debug?

Thanks and regards

Jan 11 14:34:59 NOTICE[13573] chan_zap.c: Hangup, did not find cref 83, tei 64
Jan 11 14:34:59 WARNING[13573] chan_zap.c: Hangup on bad channel 0/2 on span 8
Jan 11 14:35:03 NOTICE[13573] chan_zap.c: Hangup, did not find cref 83, tei 64
Jan 11 14:35:03 WARNING[13573] chan_zap.c: Hangup on bad channel 0/2 on span 8
Jan 11 14:35:20 NOTICE[13573] chan_zap.c: Hangup, did not find cref 84, tei 64
Jan 11 14:35:20 WARNING[13573] chan_zap.c: Hangup on bad channel 0/2 on span 8
Jan 11 14:35:24 NOTICE[13573] chan_zap.c: Hangup, did not find cref 84, tei 64
Jan 11 14:35:24 WARNING[13573] chan_zap.c: Hangup on bad channel 0/2 on span 8
Jan 11 14:35:44 WARNING[13573] chan_zap.c: Whoa, there's no  owner, and
we're
having to fix up channel 22 to channel 23
Jan 11 14:37:44 WARNING[13568] chan_zap.c: 3 received SETUP message for call 
that is not a new call (retransmission).
Jan 11 14:37:54 WARNING[13568] chan_zap.c: 3 received SETUP message for call 
that is not a new call (retransmission).
Jan 11 14:38:04 WARNING[13568] chan_zap.c: 3 received SETUP message for call 
that is not a new call (retransmission).
Jan 11 14:38:14 WARNING[13568] chan_zap.c: 3 received SETUP message for call 
that is not a new call (retransmission).
Jan 11 14:38:24 WARNING[13568] chan_zap.c: 3 received SETUP message for call 
that is not a new call (retransmission).
Jan 11 14:38:34 WARNING[13568] chan_zap.c: 3 received SETUP message for call 
that is not a new call (retransmission).
Jan 11 14:38:44 WARNING[13568] chan_zap.c: 3 received SETUP message for call 
that is not a new call (retransmission).
Jan 11 14:38:54 WARNING[13568] chan_zap.c: 3 received SETUP message for call 
that is not a new call (retransmission).