Vist Machine cannot see XP machine on Network

I hope someone can help me with this.
I have a Vista machine and a XP machine networked together on a small home
network. The XP machine is running XP professional 5.1 with Service pack 3;
the Vista machine, Vista Home Premium 6.0 service pack 2; Both are connected
using a linksys wireless router. The Vista machine is hard wired into the
router and the XP machine is wireless. Everything worked as it should until
a few weeks ago when I was no longer able to access the XP machine or its
files from the Vista machine. When I view the network map from Vista I can
see the XP machine on the map but there is a broken line (dotted line)
between the XP machine and the router. Additionally there is an icon for a
switch between the Vista machine and the router. I have never seen the switch
icon on the network map before. I have internet access for both machines and
I am able to share printers that are on the network without any problems at
all; I just can’t access the XP machine from the Vista Machine.
This is what I have done so far to correct the problem.
1) Ran the network wizard utility from the XP machine and completely set up
the network from scratch (many times)
2) installed the hot fix # KB922120-V6 from the Microsoft support site.
3) Reset the router.
Both computers and the router have a different IP address… I think this is
the way it’s supposed to be but I’m not sure.
I can ping the router and the Vista machine from the XP machine perfectly.
From the vista machine I can ping the router OK but I CANNOT ping the XP
machine.
Any suggestions? Please?

 

Hi
Make sure that the Software Firewall on each computer allows free local
traffic. If you use 3rd party Firewall On, Vista/XP Native Firewall should
be Off, and the active Firewall has to adjusted to your Network IP numbers
on what is some time called the Trusted Zone (consult your 3rd Party
Firewall instructions.
General example, http://www.ezlan.net/faq#trusted
Vista File and Printer Sharing-
http://technet.microsoft.com/en-us/library/bb727037.aspx
Windows XP File Sharing -
http://support.microsoft.com/default.aspx?scid=kb;en-us;304040
Printer Sharing
XP -http://www.microsoft.com/windowsxp/using/networking/expert/honeycutt_july2.mspx
Windows Native Firewall setting for Sharing
XP -http://support.microsoft.com/kb/875357
Windows XP patch for Sharing with Vista (Not need for XP-SP3) -
http://support.microsoft.com/kb/922120
When done hard reboot all network computers and the Router.
Jack (MS, MVP-Networking).