Index: trunk/kernel/admin_templates/incs/grid.js
===================================================================
diff -u -r5031 -r5035
--- trunk/kernel/admin_templates/incs/grid.js	(.../grid.js)	(revision 5031)
+++ trunk/kernel/admin_templates/incs/grid.js	(.../grid.js)	(revision 5035)
@@ -31,8 +31,13 @@
 	if (!this.AlternativeGrids[$source_prefix]) return false;
 	
 	var $i = 0;
+	var $destination_prefix = '';
 	while ($i < this.AlternativeGrids[$source_prefix].length) {
-		this.Grids[ this.AlternativeGrids[$source_prefix][$i] ].ClearSelection();
+		$destination_prefix = this.AlternativeGrids[$source_prefix][$i];
+		if (this.Grids[$destination_prefix]) {
+			// alternative grid set, but not yet loaded by ajax
+			this.Grids[$destination_prefix].ClearSelection();
+		}
 		$i++;
 	}
 }