a hard crash / kernal panic

Many 0s in a log file show like this:
^@^@^@^@^@^@^@^@^@^@

.. Indicate a massive failure when writing the log. Probably kernal panic.

Check system level things
* /var/log/syslog   (all logs)
* /var/log/kern.log    (kernal logs)
* dmesg    (logs of kernal ring buffer - The IO for the kernal)