--- sys/dev/usb/controller/ehci.c	2011-07-08 16:48:10.000000000 +0000
+++ sys/dev/usb/controller/ehci.c	2011-07-08 16:49:18.000000000 +0000
@@ -1177,7 +1177,9 @@ 
 		sqh->prev = 0;
 
 		usb_pc_cpu_flush(sqh->page_cache);
-	}
+	} else if (last == sqh)
+		last = NULL;
+
 	return (last);
 }