I can consistently connect successfully to both the router and the internet using both my phone and two different computers which strongly suggests that the issue is at the desktop end.

Only my Windows 7 desktop machine has stopped getting internet connectivity. It manages to connect to the router's network using the Windows 7 wireless dialog, but can't access either the router configuration page (192.168.1.1) or the internet in general once connected. The strange thing is the wireless network icon in the notification bar shows a full strength signal, sometimes with the yellow warning triangle. The output of ipconfig /all is:

Wireless LAN adapter Wireless Network Connection:

Connection-specific DNS Suffix  . :
Description . . . . . . . . . . . : Broadcom 802.11g Network Adapter
Physical Address. . . . . . . . . : 00-12-17-94-98-90
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IPv4 Address. . . . . . . . . . . : 192.168.1.102(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : 08 June 2011 10:32:16
Lease Expires . . . . . . . . . . : 08 June 2011 12:32:16
Default Gateway . . . . . . . . . : 192.168.1.1
DHCP Server . . . . . . . . . . . : 192.168.1.1
DNS Servers . . . . . . . . . . . : 194.168.4.100
                                    194.168.8.100
NetBIOS over Tcpip. . . . . . . . : Enabled

I've tried

• renewing DCHP settings
• disabling IPv6
• resetting TCP stack
• uninstalling and reinstalling WLAN card drivers

I've not installed anything new or made any changes to my knowledge, this just happened out of the blue. The only possible change is my friend connected his macbook to the network, but that has gone now and shouldn't have any lasting effects? TCP/IPv4 is set to automatically find an IP address. Antivirus is MSE (up to date) and doesn't detect anything unusual. Any ideas where to go next? Any help is greatly appreciated.

For reference, the results of ipconfig /all on one of the working computers is:

Ethernet adapter Wireless Network Connection:

    Connection-specific DNS Suffix  . :
    Description . . . . . . . . . . . : Broadcom 802.11g Network Adapter
    Physical Address. . . . . . . . . : 00-16-CF-67-E5-97
    Dhcp Enabled. . . . . . . . . . . : Yes
    Autoconfiguration Enabled . . . . : Yes
    IP Address. . . . . . . . . . . . : 192.168.1.100
    Subnet Mask . . . . . . . . . . . : 255.255.255.0
    Default Gateway . . . . . . . . . : 192.168.1.1
    DHCP Server . . . . . . . . . . . : 192.168.1.1
    DNS Servers . . . . . . . . . . . : 194.168.4.100
                                        194.168.8.100
    Lease Obtained. . . . . . . . . . : 08 June 2011 10:26:38
    Lease Expires . . . . . . . . . . : 08 June 2011 12:26:38

UPDATE: Still not working, but I've managed to find a temporary workaround by tethering my Android phone, effectively becoming a new wifi adapter. Will be moving to a new flat so will test if it is a network specific thing - maybe the card has got damaged somehow? Also will see if the card is working with Linux soon.