My Vista (32) SP1 laptop that had connectivity problems which were fixed
a month ago has now developed another problem: At some point during the
day, it will simply get "tunnel vision" and see ONLY the Internet,
nothing on my LAN. Other computers (3 - all running XP Pro) cannot
'see' the Vista machine either where prior to this happening they could.
At NO time do the XP machines lose connectivity to the Internet or the
LAN or each other.

The previous laptop problem involved a wired connection instead of the
usual wireless connection that Vista apparently enforces. Once I fixed
that problem it remained stable for almost three weeks. Turned out that
the IPv6 driver needed replacing with an update (that only RadarSync was
able to tell me)(NVIDIA nForce 10/100/1000 Networking Controller).

As my wireless Access Point is still down, I am forced to connect using
a CAT-5 cable through a switch to my router. When directly connected to
the DSL modem, I stay connected without a hitch. When I am in my
computer room I am back to the chain of equipment as before. All cables
have been swapped with cables running to the XP machines as well as
swapping slots in the switches. Pulling the CAT-5 plug out, pausing,
and plugging it back in will only disconnect & connect the Internet
connection but not reconnect to the other computers. I have checked the
properties for the wired NIC and verified that nothing can put it in
power-down or sleep mode. I do not put my laptop in sleep or
hibernation at all - the most I do is let the screen go blank after 10
minutes of inactivity.

Results of a PING on the Vista machine to any of my XP machines will
give me "The ping request could not find host 'xxxxxx'. Please check
the name and try again." ('xxxxxx' is the name of any of my XP
machines). It is almost as if the XP machine names have been deleted
from the hosts file - but they come back when I reboot.

If I reboot the laptop the full connectivity comes back: to the
LAN/Internet and all the XP machines. I can pass files/whatnot between
them freely. At some point pretty much every day, the Vista laptop will
'remove' itself from the LAN and remain hidden from the other machines
until I again reboot it.

I wrote a tiny program and tries to access the laptop every 20 minutes
and put it on one of my XP machines. Once connectivity is lost, it
alerts me. Usually, this happens while I am busy on an XP machine and
have neglected the laptop for varying amounts of time. MY error message
is "The laptop disappeared again!"

Is this just some sort of Vista glitch that has no real fix or is there
something I've failed to check? I've seen loads of posts here detailing
a lot of IP configuration/driver issues and have read each one with an
eye to solving this latest headache.

GP

I forgot to mention also the when this happens, any IPCONFIG
configuration command (such as /renew) will tell me (approximately, as I
didn't write it down) "this command cannot be executed until the adapter
is connected to a network". It will, however, tell me that my static IP
address and everything else is correct. Clearly the computer thinks the
plug has been pulled BUT the fact remains that I can open a browser and
surf the Internet at will. Very strange.

GP

Further troubleshooting finds that any attempt to Disable the adapter
(when Enabled) or Enable the adapter (when Disabled) will cause
Explorer.exe to stop responding and force me to use the PM to kill the
process. In the midst of killing the process the computer becomes
completely unresponsive and I have to hold the power switch down.

On power up after doing that it runs checkdisk (which I expect) and
starts normally. If I go directly to the Network Device Management I
see that whatever operation I started (Enable or Disable) has been
completed and the device is in the state I wanted it to be in. If I
immediately try to reverse that state I go through the complete
hang/kill/power cycle/cold start/normal restart process again.

Clearly "something is wrong" but I cannot determine just what it is.

GP