shmmax

http://2bits.com/articles/high-php-execution-times-drupal-and-tuning-ap…

Fortunately I found the solution here http://thread.gmane.org/gmane.linux.drivers.ndiswrapper.general/3121 , which is to add these lines to /etc/sysctl.conf, and run "sysctl -p" to update the settings:
kernel.shmmax = 67108864
kernel.shmall = 67108864