We have an employee whose surname is Null. Our employee lookup application is killed when that last name is used as the search term (which happens to be quite often now). Th
As a hack, you could consider having a special handling on the client side, converting 'Null' string to something that will never occur, for example, XXNULLXX and converting back on the server.
It is not pretty, but it may solve the issue for such a boundary case.