Index: wp-includes/wp-db.php
===================================================================
--- wp-includes/wp-db.php	(revision 5994)
+++ wp-includes/wp-db.php	(working copy)
@@ -227,11 +227,13 @@
 			$return_val = $this->rows_affected;
 		} else {
 			$i = 0;
+			$this->col_info = array();
 			while ($i < @mysql_num_fields($this->result)) {
 				$this->col_info[$i] = @mysql_fetch_field($this->result);
 				$i++;
 			}
 			$num_rows = 0;
+			$this->last_result = array();
 			while ( $row = @mysql_fetch_object($this->result) ) {
 				$this->last_result[$num_rows] = $row;
 				$num_rows++;
@@ -428,4 +430,4 @@
 
 if ( ! isset($wpdb) )
 	$wpdb = new wpdb(DB_USER, DB_PASSWORD, DB_NAME, DB_HOST);
-?>
\ No newline at end of file
+?>