I'm getting intermittent errors in my Apache error_log like this:
sql: mysql_connect() [<a href='function.mysql-connect'>function.mysql-connect</a>]: Connection timed out - /page.html - sql: Failed to connect to db: - /page.html - sql: mysql_connect() [<a href='function.mysql-connect'>function.mysql-connect</a>]:  Connection timed out (trying to connect via tcp://db1.domain.com:3306) - /page.html
I can ping db1.domain.com (which is defined in my /etc/hosts file), I can telnet to db1.domain.com on port 3306. I can even use the cli mysql client using "mysql -h db1.domain.com -p"
There are no rules in iptables and I can't see any packets being dropped on the NIC on ifconfig. There are no firewalls between this server and the database server.
This is 1 of 6 webservers we use to serve our website, the other 5 are not showing the same errors.
Is there anywhere else I can check for problems?