After logging on to R/3 I got the GuiXT license popup. I clicked on "System->Status>Activate GuiXT", and it worked fine during this session. But each time I now logon to R/3 I have to perform the same GuiXT activation steps again. What can be done ? 

You probably work with a guixt.ini file where you specified "IgnoreRegistry Yes". There is a bug in GuiXT, corrected with version 2001 Q3 02, which forces you to do the activation for each logon in this case. Solution: Either you install a new GuiXT version or you work without the "IgnoreRegistry Yes" option.