Error -- Could not open /var/www/ to write file lock

A lock is a file which is written before modifying the data and removed afterwards to prevent corruption by two simultanious processes. The directory, /var/www/ has been defined on lines 6and 7 of the /var/www/ script.
The /var/www/ script must have read/write permissions to that directory in order to place the file lock.

You can disable the file lock on the "customize pages" screen.