Apache seems to crash with this error : [notice] child pid x exit signal File size limit exceeded (25).
This usually means that a log file has grown too large for the system (generally 2Gb).
A quick fix will be to run the following commands as root via SSH.
/scripts/updatenow /scripts/biglogcheck -v
If you have extremely large/active sites that reach this limit quickly, you might consider disabling logging for that site alltogether. You lose the webstats for it but you gain a decent speed increase and you don’t have to worry about it dropping apache.