Headers And Client Library Version Mismatch Errors

Getting the following errors at the top of my site pages now:

Warning: mysqli::mysqli() [mysqli.mysqli]: Headers and client library minor version mismatch. Headers:50542 Library:50623 in /home/whdcocom/public_html/2afirearmsdealer/core/db/mysqli.php on line 57

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/whdcocom/public_html/2afirearmsdealer/core/db/mysqli.php:57) in /home/whdcocom/public_html/2afirearmsdealer/core/class.session.php on line 271

Warning: Cannot modify header information - headers already sent by (output started at /home/whdcocom/public_html/2afirearmsdealer/core/db/mysqli.php:57) in /home/whdcocom/public_html/2afirearmsdealer/core/fn.init.php on line 413

Long story short, looks like my PHP version was updated, gave me 500 error codes on my site, they dropped the PHP version back down, and these errors appeared.

Any ideas how to fix this?

Thanks in advance.

http://2afirearmsdealer.com

Looks like version of mysql not appropriate for php version.

It is not a cs-cart issue, but server related. Please inform sever administrator about these errors.