I have an installation of Magento 1.9.2. I am using a custom theme, and anytime I try and place an order it kicks off the Ajax on the page and then stops with no error messages, but does leave a log:
ERR (3): User Error: Some transactions have not been committed or rolled back in /html/lib/Varien/Db/Adapter/Pdo/Mysql.php on line 4039
I have spent 2 days trying to get to the bottom of this with no joy. It doesn't matter what payment method I use its always the same.