Upgraded my PowerBook G4 yesterday from 10.3.9 to 10.5.1 without real problems. I am using X11 regularly, for example gv (ghostview), but it could not open the DISPLAY. So, I installed the X11 version coming with 10.5 DVD. Installed fine, all programs are there, however, I still cannot open any window. Even the xhost command complains: _X11TransSocketINETConnect() can't get address for 0:6000: nodename nor servname provided, or not known xhost: unable to open display "0:0" Even if I set the DISPLAY variable, it still complains: xhost: unable to open display "188.8.131.52:0" Any ideas? A less important issue is that X11 creates a second icon in the dock after startup, besides the one I am keeping always in the dock. Read about that earlier with GIMP, but that seemed a GIMP issues at the time. Thanks for any help in advance!