So you're saying that at one point, phpinfo showed all the modules working, and later, without changing anything, it doesn't? Doesn't make much sense.
What happens when you do 'rpm -q php-mysql'? Don't add the version or anything else, just php-mysql.
If you take a look at /etc/php.ini, is there a place that says 'extension = mysql.so'?
If you try restarting httpd (with '/etc/rc.d/init.d/httpd-e-smith restart'), what does the phpinfo page say then?
What is the output of 'rpm -qa | grep php'?