New computer oddly won't connect to WiFi...

What happens if you select other network and manually enter the network name and password, does it connect?

 

Glad it is working for you again. Maybe the channel that you are using was affected at the time you tried to use the WiFi. A selected WiFi channel can be affected by how many users are using that channel. If you want to see this in action:

1. Hold down the option-key and click on the WiFi icon in the menubar.
2. Select "Open Wireless Diagnostics...".
3. Click Window->Scan from the Wireless Diagnostics menu.
4. Click Scan Now.

This will show you all the detectable WiFi networks around you, including your own network(s), and show you what channels are being used. If you find that a lot of people are using the same channel as you, then you might want to pick another channel that is being used far less. This could help your WiFi stability.

 

Then dowload the trial shareware iStumbler and run it. If your wireless network is on the same channel as others around you then go into your router at change the channel. This will help your network.