Registry Date length resetting.

I’m running Citrix on Terminal Server and I have a problem. I need the date format on the locale setting to be dd/mm/yyyy. However something is writing back the format to be dd/mm/yy which causes big problems with one of my apps. I’m using policies instead of roaming profiles. I’ve tried editing the users registry settings directly as well as editing the NTConfig.POL through the registry editor and I’ve also tried using the policy editor itself. I’ve also changed the ‘default user’ settings butsomething is still writing back the default settings. Does anyone know what it is? HELP!!!!