MySQL PDO Cannot assign requested address Can someone help me with this error?

[08-Apr-2013 17:44:08 Europe/Berlin] PHP Warning:  PDO::__construct(): [2002]
    Cannot assign requested address (trying to connect via tcp://****:3306) in 
    /var/www/***
[08-Apr-2013 17:44:08 Europe/Berlin] PHP Fatal error:  Uncaught exception 
    'PDOException' with message 'SQLSTATE[HY000] [2002] Cannot assign requested 
    address' in /var/www/***


I have a Server with a lot connections per second; out of about 100 Connections, a single one got this error.

I've tried this recommendation from stackoverflow however it does not solve my problem.
You could also be hitting max open files (sockets) under Linux. You can change this in /etc/security/limits.conf.