Unwanted Movement Trails

Following the last SL update I have started to see movement trails following moving objects / people. They appear as rising red / blue cones which then follow the movement of the object. I have been told that it is something which can be turned off in the Client menu but I can't find anything. Any help appreciated as it is really annoying especially in crowded places. Thanks

I am not in-world to test, but I believe that CTRL-ALT-U will toggle this "feature".

Thanks very much. You were almost right I played about and discovered it is Shift-CTRL-ALT-U.

Thanks again it has been driving me wild.