"The connection closed unexpectedly" - Error on Windows XP client machine

[Noah-John Gellner]

I would be most grateful if anyone can help me address my network 
connectivity issues.

There are three routers that are connected on my home network, but only two 
have computer connections.

1. Router 1 is a Netgear router/print server and is connected to the WAN 
192.168.0.1. Linux Server is connected to this router as 192.168.0.9.  
Router 1 is the firewall.  I want to use VNC to connect to this Linux 
Server.
2. Router 2 is a Linksys wireless router and is only used by the wireless 
laptop. It has IP 192.168.0.10. DHCP is not active on this router, rather 
DHCP is served by Router 1.  The XP client that has connectivity problems 
connects to the LAN via Router 2.
3. Router 3 is a Netgear/VOIP router for Vonage.

>From the XP client laptop I am able to connect to the internet, print to the 
printer attached to the Router 1 print server. I can mount network drives 
from a Windows box attached to Router 1 but cannot open a VNC connection to 
that machine. The Windows box on Router 1 can connect a VNC session to the 
laptop on Router 2.  The Windows box can also open an ssh-tunnelled VNC 
session to the Linux Server either via LAN IP or by WAN IP.

The linux box on Router 1 uses ddclient and a free dns service to be 
available from the internet. I can ssh to the box using either its LAN or 
WAN address on the problem client laptop. I have set up an ssh tunnel to 
tunnel VNC. The problem is VNC does not connect either locally or via the 
internet hostname.

Any ideas about the VNC problem? The error message is "The connection closed 
unexpectedly" and takes a while to pop up.

Both Windows machines use Windows XP with most recent updates, VNC 4.1.1.

I have read the related posts in the archives of this mailing list and have 
looked for solutions elsewhere on the internet.  There are no Events logged 
when VNC fails.

I believe there is a problem with the configuration of the problem laptop 
and I am eager to address it.

Thank you all kindly in advance.