@dcharlesworth
Let us know if that driver works. As far as 'It was working a month ago' goes, my experience is this: Sometimes everything works. I have two routers. The wireless card seems to go through periods of being 'cranky' where it doesn't want to talk to one or the other. That seems to last a good while, days or weeks maybe. I don't pay that much attention any more, just switch routers if I have trouble and usually I'm fine for a while.
Mostly it has trouble with my Verizon issue one, but once in a while it's the Time Capsule. Both are 802.11n and I've changed channels, encryption, every other damn thing when I was first trying to troubleshoot. It seems to have nothing to do with rebooting. I rebooted dozens of time when first troubleshooting, applying various fixes, and it didn't help.
I've seen some people, like you, who think they're timing out from inactivity. In fact I've seen people systematically prove it for their cases. For me, though, I've had it cut me off in the middle of downloads, streaming netflix, and active browsing sessions.