If so, my first guess would be that its something to do with the working directory of the script.
I would always use full paths to everything, starting from the server root, rather than using `cd`.
Assuming /srv/www/current is the root of the Alaveteli app, something like this:
31 * * * * deploy RAILS_ENV=production /srv/www/current/commonlib/bin/run-with-lockfile.sh -n /srv/www/current/load-mail-server-logs.lock /srv/www/current/script/load-mail-server-logs || echo "stalled?"'
If you send over your full crontab file I'll take a look.
Cheers,
Gareth