I have now had my brand new replacement Treo 600 for about two weeks and dust has appeared behind the screen (again !). This is is exacltly the time scale that elapsed before the previous phone devloped this fault. The dust appears to settle in the uppper third of the screen (inline with the earpiece) and is mainly visible when the screen is off and viewed at an angle such as in its cradle. Both Palm One and A-nuvo claim this to be a new problem and not one that they have heard of before.
Have I just been unlucky or have other Orange UK users had the same problem.