Hi Vlk,
i checked the service. The "local system account" is marked. I think it is right, isn't it?
There is another aspect i figured out. On the system with win xp sp1 it works fine, but on machines with win xp sp2 there are the problems. I think it may be, because of the window firewall, so i deactivate the firewall, but nothing happened. May be there is an problem with sp2, i've got no idea.