Really weird Windows 7 wifi connection issue

Helped a client of mine set up their computers at their new house. They have one of those HP TouchSmart all in one PCs with a built in wifi adapter. It originally came with Vista, but they installed Windows 7 on it at some point. When attempting to connect to their wireless network, Windows kept throwing an error indicating that it could not connect to the network. The troubleshooter said it was an error with the router. The password was correct and everything worked in their old house (different wireless router).

Here's what I tried:

- Disabled all security on the router
- Tried a different USB wireless adapter, disabled built in wifi
- Connected one of their old wireless routers (Netgear) to their gateway (Xfinity Arris tg862) and set it up as an access point. I changed the wireless SSID on the Arris and made it hidden since you can't disable wifi on it (WTF?). All devices could see this network and connect to the internet, but I was getting the same error on their computer, but this leads to the next point...
- Their computer WOULD connect to the new wireless network on the Netgear as long as the router was not connected to the Arris.

Yesterday I was temporarily able to get the computer to connect to the network, but once it connected, it would drastically slow down everything else on the network. I had "ping -t google.com" running on a second computer and I observed response times go from ~30ms to ~3500ms as soon as this computer connected to the network.

I was not able to attempt a connection via Ethernet because the data port in their office was dead due to the electrician not labeling the cable ends in the equipment closet. I will have to go back another day with my cable tracer so I can terminate the end of the appropriate cable and hook it up directly to the gateway.

Any ideas? I have never seen such a strange issue in all my years of doing this.

 

Not following what you are trying to do. If you are having problems connecting to the router with the computer, first thing you should be doing is removing the driver for the networking adapter, remove any other plug in USB adapters, then let Windows 7 find the default Windows 7 driver, or check at http://www8.hp.com/us/en/support-drivers.html for the Windows 7 driver.

As for slowing down the network, you probably were packet flooding it, by having multiple adapters connecting to it from the same computer.

 

If it were a driver issue, why was I having the same issue with both adapters and why was I able to connect to another wireless network without any issues whatsoever?

Either way, I forgot to mention that I did remove the driver for the built in wifi adapter and updated it with the most recent release. Also, I attempted a system restore back to well over a month ago - before they moved and when the internet connection on this computer still worked.

This happened before I tried the second adapter (also forgot to mention this)

I'll be back at some point this week to wire up the data port in their office and attempt a connection over Ethernet.