I have established that the symptoms are the same if i use Tomahawk's datalist in place of the datalist provided by richfaces, additionally the same thing still happens if i use the tomahawk jscookMenu with either datalist and t:navigationMenuItem but my menu works correctly if i use t:navigationMenuItems (which does not require the use of a datalist).
this solution is not ideal because the whole point of using richfaces is to take advantage of the ajax features which are not provided by tomahawk.
i am not sure if there is any shared code between richfaces and tomahawk or whether this is a bug (maybe in myfaces rather than richfaces).
anybody got any ideas????