Hallo Thimi,
schaue Dir einmal diese drei Info Apars der IBM an:

http://www-912.ibm.com/ImprovedSearc...all%20Products

Windows XP SP2 Can Muck with iSeries Access
by* iSeries NEWS staff *

September 02, 2004 —* Rochester's iSeries Access (aka Client Access) team has published a support document explaining that the default firewall enabled in Windows XP Service Pack 2 (SP2) can shut down communication between the iSeries host and Windows client when using iSeries Access for Windows. The problem is that the default firewall blocks the incoming communications that iSeries Access depends upon.
That doesn't mean you can't use SP2 with iSeries Access. The support document goes on to explain how to configure Windows firewall to make an exception for iSeries Access. For more information, see the support document, "iSeries Access for Windows and PC Firewall Products."