I have three PCs, one Vista laptop, one Vista desktop, and a XP desktop I
use as a server. The laptop used to use wireless and now uses a LAN, but in
Network and Sharing center it identifies a proper network. My main home
built desktop runs Vista home premium SP1 OEM and refuses to recognize the
LAN its connected to. The three PCs are connected to a Gigabit Linksys
switch, the switch is connected to a Linksys wireless router, and the router
is connected to a DSL modem for internet access. MAC addresses were
configured in NIS 2009 as trusted PCs for all devices. With NIS 2009 on or
off, Vista still says I don't have a network.

On the Vista "not connected" desktop, Start, Network; displays all of the
network devices, PCs, a broadband router, and even my DirecTV media share
DVR! Unfortunately there is a yellow bar that reads " The computer is not
connected to a network, Click to connect... When I click on that bar it
says I don't have any wireless networks. I don't, for the PC is CONNECTED
TO A LAN SWITCH! But a wireless network is all it offers to connect.
Network and Sharing center reads NOT CONNECTED, nothing, I keep getting
"This computer does not have a wireless network adapter installed and
configured"; of course not, it's on a LAN. There's no customize button to
change from Public to Private.

PLEASE READ... The kicker here is ALL THE NETWORK FUNCTIONS WORK on the
non-network. I can share files, printers, use the server to backup files on
the desktop, the DSL internet connection work great, I can even play video
from my DirecTV DVR. Literally everything works!

Why won't Vista allow me to create a recognized LAN??

With NIS 2009 on or off, Vista still says I don't have a network.

Which begs the obvious suggestion... remove NIS, reboot, reboot again and
see if the network properly appears.