Cannot Create a Full Network Map in Vista

When I open the Vista Network Properties and click on "view full map" I
receive the following message: "Windows cannot create the network map.
Responses from other items on the network are delayed or there is an
incompatible router on the network."

I am able to view the computers and share files and printers with the other
computers on my network (all XP - I have the "Link Layer Topology Discovery"
enabled on all of the XP computers).

This mapping function was working fine until one day it stopped. I have a
Netgear WPN824 router and my firmware is up to date. Everything else seems
to be working fine. I do not have any nVidia network components - I noticed
in other posts that there is a problem with a specific nVidia network driver
(I do have an nVidia graphics card, but I do not believe that should not
affect this). I am running Vista Ultimate.

The Link Layer Topology Discovery is enabled in my wireless settings.

Any suggestions?

Thanks in advance!!!!!!