Can't Get Past Router

I have an Acer TravelMate 2420 and Speedstream 6250 router/dsl modem.

With a 128-key code, the Acer would not connect to the router and would not
receive an IP.

With a 64-bit code, it will connect and pick up a router-assigned IP address
(192.168.2.10). Ping test to the router are successful, and it is possible
to see the router's web interface. But ping tests to Internet servers won't
work, and no Internet applications work.

A wired connection with wireless on the Acer turned off does the same thing.
An IP address is assigned (192.168.2.12) to the notebook and ping tests to
the router are okay, but anything beyond on the Internet is impossible.
Turned off Windows Firewall, same result.

A wired connection using another desktop computer works fine.

Other laptops can't connect wirelessly to the Speedstream router.

Connections from the Acer to other wireless networks are successful with
full IP functionality.

Given that the Acer can connect to other wireless networks, it really seems
like the problem lies with the router. It's been software restarted several
times (wait 45 seconds).

Any assistance is appreciated.