check to see if squid has filled up its partition, if so, set the cache_dir directive in /var/chroot-squid/etc/squid.conf-default to 60% (or so) of the partitions capacity...
Did the machine reboot or did the syslogd just restart? If the machine did reboot, are there indications in the other files that the machine restarted gracefully? [Is it hardware or software causing the reboot?]