How do I fix this Windows 7 wireless connectivity issue?

Question

I have a laptop with an Intel Wireless Centrino 6300 module. Recently, the machine has stopped properly connecting to my wireless router. It will get stuck in a loop of connecting, then disconnecting and reconnecting. While connected, it will simply say "No Internet Access."

Running inSSIDer 2.0, it shows my network jumping around between two channels -- I know this isn't the case, because I've set my router to sit on one single channel. My MacBook Pro, Boxee Box, PS3, and Xbox 360 all connect fine to the wireless and have no problems at all.

I know it's not the wireless module, as I bought a second one recently assuming the first had died -- but I get the same behavior with both.

Sometimes, I can fix the issue temporarily by deleting the network (Using the Manage Wireless Networks page), and then re-adding it (via standard wireless methods). Then it will work for a few days.

Additional info: Sometimes I can set the channel on my router (A Buffalo WZR-HP-G300NH running DD-WRT build 14896), and the laptop will stay connected. Sometimes I put it on auto, and the laptop will stay connected. But eventually it drops back to failing to stay connected. But sometimes it just seems any change at all will cause it to connect.

Worth noting that whatever I do, all my devices continue to hold a connection without issue.

But inevitably the problem comes back, and now the laptop simply won't connect to the wireless at all, even if I take steps that usually work.

Since I've ruled out the hardware, and it's unlikely some kind of interference issue (because I would expect to see it on any multitude of other devices), I would think at this point that it's a problem with Windows itself.

One thing that might be a hint, even though I delete the network, when I add it again, it's always listed as "Wireless Network Connection 2" even though there isn't another in the list.

Another fix I've just found (knock on wood) is to set my router to only do G and N. This isn't a great solution since some of my devices don't use N, and I don't know that it will work long term.

Also, I've asked another question which could very well be related: What is the correct antenna configuration for an Intel Centrino 6300 module on a Dell Studio XPS 16?