Question : Enable UltraVNC to connect across subnets

We have multiple Win XP machines on site on 2 different subnets.  We recently upgraded our UltraVNC software from version 1.0.2 to 1.0.5.  We added the software to our PC image so that when we reimage a machine, VNC is installed and we can remote connect to it.  Unfortunately, unless the reimaged PC is on the same subnet as the computer we're connecting from, we cannot connect to the computer.  

Any ideas where to look?  Firewall ports are open on the reimaged machines.  We're clearly missing a step in the setup that we lost in the upgrade.  

Thanks!

Answer : Enable UltraVNC to connect across subnets

We figured it out.  The way we were reopening the ports after reimaging was by using netfw.inf and calling "netsh firewall reset" on startup.  The instructions we found for altering netfw.inf included setting the open ports to "LocalSubnet" rather than "*" which allows them to be accessible from any subnet.  Changing this fixed the problem.  Thanks anyway for your help!