I bought Skyrim Because of the great deal going on right now ($19.20), also just built a new pc gaming rig. I'm using a wireless keyboard and mouse combo witch run off of a single Usb wireless receiver. i have a Microsoft wireless keyboard 3000 V.2 and a Microsoft wireless mouse 5000, I'm also running windows 7 ultimate. when i get in game my mouse works and my keyboard doesn't even though i disabled the gamepad, If i plug in a separate keyboard it works just fine. I've searched for fixes for similar problems but found no solutions.
Drivers, more than likely. I don't know why you would run wireless for both devices (especially them on the same reciever) in the first place, but that's bound to cause problems on its own.
Also, if you have any other peripherals, like a wheel, stick, etc, unplug those. I get problems regularly if I leave one of mine in without using it, like constantly turning left in games with the wheel plugged in. Once spent an hour trying to figure out why I kept doing circles in DaS before I thought of my wheel.
unplugged my headset (turtle beach px21) rebooted the game and now my keyboard works @_@. no idea why this works now but it does.
i spent like 80bucks like 3years ago on this combo so i could sit across the room and play games and watch movies on a tv, didn't really think anything of the single receiver it came with for both peripherals.