Wireless network is connected but no internet access

Check your router setup to ensure access to the internet from wireless clients is enabled.

I have an odd case in a repair job I did (well, setup really) that's not worth creating a new topic for:

I installed a Lynksis wireless router, put a new computer on a wired connection & installed a wireless NIC on an old computer they wanted in a different room. I did a few reboot tests on everything - it all checked out & kept working (although the wired computer was working slower just browsing until I told the router to keep the internet connection dialed in constantly - why would that even be an option?) but they called me back a few days later:

The hardware is still getting a full connection, but now the computer connected by wire still has internet, while the computer connected by wireless isn't getting any browsers to work.

It was all very vague - my information is currently just over the phone from people who can't tell monitors from computers. It's difficult to say what they may have on their hands - though I did get out of them that the hardware itself is still working.