Occasional Rsync Failures

I am running rsync 2.5.6 on Solaris 9 as a means of replicating data
between two remote servers. At least once a day, at varying times, the
process fails during the transmission of data. The command I'm using
is:

rsync -avvvvz -e ssh --rsync-path=`which rsync` --delete <remote
hostname:/<path/> <local path/> >> $log

The only error detail I am seeing is this:

[3826] i=345257 REALTIMEPIN/APPOINTMENTS/2005_9
2005_9_16_23_7_22(11141070-RESPONSE).xml mode=0100644 len=1571
_exit_cleanup(code=12, file=io.c, line=165): entered
_exit_cleanup(code=12, file=io.c, line=165): about to call exit(12)

Any theories on what might be happening? I have sufficient disk space
on both systems.

Thanks in advance,
Dave