Do you have a value filled in for this in config for you board:
Log all mysql errors? If you want to do this you will need to specify a path to a directory here. This directory should be outside of your document root and will need to be writeable by the webserver.
If so you should be able to view the error logs through the admin panel.
Then you will be able to view the errors that these refer to:
SQL ERROR: Database error only visible to forum administrators
