mod_security might well prevent your system from working (but I don't know if LP uses it). Note that it can't possibly directly corrupt your database -- it just prevents certain data from being passed through GET or PUT. It's a strange coincidence if just while restoring your database, LP happened to change mod_security settings. More likely, there's something wrong with your database setup, or your backup was corrupt. Also check your own .htaccess files to make sure they're not breaking QUERY_STRINGs.