No connectivity over secure connections

My system: hp Pavillion dv9700 w/ Vista Ultimate, less than a month
old. Wireless adapter Intel Wireless WiFi Link 4965AGN. Wired network
adapter: Realtek RTL8168B/8111B Family PCI-E Gigabit Ethernet NIC.
Both adapters factory-installed & had worked without incident until
today (well, technically yesterday, but whatever).

Forgive the long-ish narrative. The ipconfig /all log follows at the
end if you want to skip a bit. I've read through the group's messages
from the last few months and found several similar problems, and have
tried a couple of non-invasive solutions (avoiding regedit and the
like), but in my reading no one has come back with this exact problem.
I've tried to include information MVPs have asked for in other
scenarios, but let me know if there's some other metric you need. I'm
not a network guy by trade (obviously).

The narrative:
Wireless (and wired) networking ceases to function over secure
connections. I am able to connect to the internet over unsecured, open
wireless connections, which is how I'm posting this now.

During the afternoon, I made an abortive attempt at work to make my
computer see the wired network. After running into problems, I
(thought I) cancelled the changes. I noticed at some later point in
the afternoon that my gTalk balloon was grayed out (not connected),
and I couldn’t reconnect to the wireless network at my office I’d been
using without incident for the last month.

I came home and powered up the computer, and it wouldn’t connect to
the home (Waterhouse, by name) network I’ve been using since the first
moment I powered up the machine just under a month ago.

Symptoms: On boot to the desktop, the connection icon in the task bar
only includes the two computers, without the little blue globe that
indicates connection to the Internet.

I have disconnected and reconnected to the Waterhouse net, without
getting Internet connectivity back. When I connect to Waterhouse in
the window listing available wireless networks, it reports that I
connect to Waterhouse successfully.

However, when I run the Network and Sharing Center, it reports that I
am connected to an Unidentified (public) network. Access is listed as
“Local Only”. When I click on the View Status link there, it opens the
Wireless Network Connection Status Window, which reports:

IPv4 Connectivity: Local
IPv6 Connectivity: Limited
Media State: Enabled
SSID: The Waterhouse
Duration: {running clock}
Etc etc

When I click on the Diagnose button:
“The network adapter “Wireless Network Connection” does not have a
valid IP configuration.”
Options are:
Automatically get new IP settings for the network adapter “Wireless
Network Connection”
A problem with you network router or broadband modem might be
preventing an Internet connection. (Unlikely, since four other
computers all use the connection just fine, and mine had been the
fifth to do so until today.)
Reset the network adapter “Wireless Network Connection.”

I’ve tried all three options. The first and third, on attempt, do not
resolve the issue. Both display incremental progress in a window
titled “Windows Network Diagnostics,” but both ultimately return with
“Windows tried a repair but a problem still exists. This computer has
limited or no connectivity.” The same three options as before are
presented.

I have asked my landlord to reset both the DSL modem and the
building’s router, both to no positive effect for me. And as I said,
there are four other computers in the house all using the wireless
connection without incident. I cannot see my other machine (a desktop)
when I open the Network desktop link, which is also a change. Formerly
I could connect to that machine and access its shared folders.

I’ve reverified the access key and protocol (WPApersonal / TKIP).

The ipconfig /all dump follows:

Microsoft Windows [Version 6.0.6001]
Copyright (c) 2006 Microsoft Corporation. All rights reserved.

C:\Users\Jason>ipconfig /all

Windows IP Configuration

Host Name . . . . . . . . . . . . : Andromeda-4
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Wireless LAN adapter Wireless Network Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Intel(R) Wireless WiFi Link
4965AGN
Physical Address. . . . . . . . . : 00-1F-3B-72-0C-5D
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::9558:199b:
5f14:ce43%16(Preferred)
Autoconfiguration IPv4 Address. . : 169.254.206.67(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . :
DNS Servers . . . . . . . . . . . : fec0:0:0:ffff::1%1
fec0:0:0:ffff::2%1
fec0:0:0:ffff::3%1
NetBIOS over Tcpip. . . . . . . . : Enabled

Ethernet adapter Bluetooth Network Connection:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Bluetooth Device (Personal Area
Network)
Physical Address. . . . . . . . . : 00-1E-37-E6-64-C4
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes

Ethernet adapter Local Area Connection:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Realtek RTL8168B/8111B Family
PCI-E Gigab
it Ethernet NIC (NDIS 6.0)
Physical Address. . . . . . . . . : 00-1E-68-52-64-BB
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes

Tunnel adapter Local Area Connection* 11:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : isatap.
{92B929D6-15A2-45E7-9A2B-74703273D
5EA}
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Tunnel adapter Local Area Connection* 14:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : 6TO4 Adapter
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Tunnel adapter Local Area Connection* 6:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft ISATAP Adapter #2
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Tunnel adapter Local Area Connection* 7:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : isatap.{78273635-
D2AE-4BF0-9E29-27F1814B5
18E}
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Tunnel adapter Local Area Connection* 12:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Teredo Tunneling Pseudo-
Interface
Physical Address. . . . . . . . . : 02-00-54-55-4E-01
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Connecting a network cable to a known active wall jack does not
restore connectivity.

Again, many thanks for any solutions.