I don't know what platform you are running MySQL on, but I know on Red Hat Linux that MySQL logging was *NOT* turned on by default. In order to turn on logging I had to modify the /etc/rc.d/init.d/mysql start/stop/status script - where it invokes safe_mysqld, I add '--log=/var/log/mysqld.log' and so changed the line
/usr/bin/safe_mysqld --defaults-file=/etc/my.cnf >/dev/null 2>
/usr/bin/safe_mysqld --defaults-file=/etc/my.cnf --log=/var/lo
+g/mysqld.log >/dev/null 2>&1 &
and remember to restart the mysqld server('service mysqld restart' on Red Hat Linux) to make the changes take effect. If you can get MySQL to log messages it might help you figure out what the problem is.