Sometimes plugins add tables to your database automatically when you install, but they are not removed when you disable the plugin. If I were you, I’d open my site in an HTML editor and do a global search for slimex_stats (or $wpdb->slimex_stats or wp_slimex_stats) to try to find where in your code that SELECT statement is being called. If your search yields any results, delete the offending code. Also, if you have access to the database, you could just delete or rename the table wp_slimex_stats. Once you do that, your PHP code in WordPress will start throwing errors indicating where MySQL is trying to run those SELECT statements and failing. You could then go to your code where the errors are occurring and delete the bad stuff.
