I am running Lenny patched up. On this machine I am running sun virtualbox virtual machine. The guest os of this machine is patched up lenny. On the guest os I am running postfix and various anti spam servers. Several times now, I find that after several days of operation, the virtual machine freezes, I can not ssh to it. I looked at the /var/log/syslog, no trace of any issues. How can I determine what caused it to freeze? Thanks in advance