I did some more checks, the problem only occurs on machines with the groupwise interims version 7.0.1 build 537 from 15/11/2006. The problem can be a groupwise bug because I have to logon to my mailbox if I first login on my workstation only local and then logon to netware and start groupwise. If I directly logon to netware during the startup of windows xp everything is ok and I do not have to logon to my groupwise mailbox.