Help! Wireless network stopped working on Tablet PC

Hello,

I'd appreciate help with the following.

My wireless network connection from my notebook pc has stopped working. It used to work and I haven't changed any setting. The situation is as follows.

The cable modem is connected to a wireless router whose IP address is 192.168.0.1 On the tablet pc, I have set a fixed IP address, 192.168.0.105 and netmask of 255.255.255.0 This used to work like a charm.

Now, after bootup, at the command prompt, "ipconfig" shows:
[code:1f128ff210]
IP Address: 192.168.0.105
Subnet mask: 255.255.255.0
Default gateway: 192.168.0.1
[/code:1f128ff210]

However, "ping 192.168.0.1" returms all failure.

The "Wireless Network Connection Status" window says:
[code:1f128ff210]
Status: Connected
Network: MyNet
Duration: 00:20:17
Speed: 11.0 Mbps
Signal Strength: (all bars lit up)
[/code:1f128ff210]

However, in the "Activity" part of the window, it shows
[code:1f128ff210]
Packets sent: 772
Packets received: 0
[/code:1f128ff210]

Other laptop (this one) continues to work perfectly with the same router.

What am I doing wrong?
What could be the problem?
How to fix it?

The only thing that I suspect is one of the auto updates from Microsoft might have messed something up.

If it matters, the pc is an Averatec C3500 and the router is a D-Link 2.4 GHz one.

Thanks

Thanks for your message.

Yes I am using WEP on the AP and on the pc.

From the log of the D-Link router, I can see that the pc in connecting successfully, with the pc's MAC address recorded correctly.
Also, no other device is using the same IP address.

I tried using DHCP on the pc and then the result is the same, i.e.

(a) on the pc ipconfig says it has connection and
(b) on the router, the pc's MAC address shows up as connected

What could be wrong?