I just recently purchased a Wireless Receiver, which kinda looks like a one-button mouse, but shrunk down. Maybe a mouse for a laptop, or for people with tiny hands. Or tiny laps.
When I opened the clamshell (by the way, the plastic doesn't need to be that level of nigh-impervious - I ordered it from Amazon, you can trust I won't shoplift it), I found the little protective piece of paper saying "hey, install the drivers before plugging this in, REALLY!". So I installed the drivers first. By the way, why can't I install the drivers after the fact? Wasn't there something called "plug and play" a while ago? Did people find it unpleasantly convenient?
And then I grabbed one of my wireless XBox 360 gamepads. Press the button on the receiver, and the button on the gamepad. Lots of blinking lights. No noticable joy, though. Again - I press the sync button on the receiver. The receiver's green LED starts blinking. I press the sync button on the game pad. The "light ring" starts lighting its LEDs in cycling sequence, then it switches over to blinking all 4 LEDs simultaneously. The receiver's light switches from blinking to solid on, but the gamepad's lights continue to blink.
I check the electronic documentation that I installed. I peruse the troubleshooting sections. The troubleshooting areas don't even have sections that seem appropriate. I check the paper documentation. There's no troubleshooting discussion at all there.
I google, and I find some people guessing that the drivers are buggy, and I find one news report saying that the receiver draws a lot of current, and that many users are finding the receivers to be useless because of it.
Eventually, I stumble across some mention that the receiver works for some people if they have it plugged into a powered USB hub with nothing else plugged into that hub.
Yikes. I had had it plugged in directly to the front of my machine, which I would have guessed would have supplied all the power that it needed, but perhaps not. I scrounged up a powered USB hub, and plugged it in. Immediately the gamepad paired up.
So, for anybody googling for "XBox 360 controller receiver not pairing up on PC" or similar keywords - get a powered USB hub and plug your receiver into that, and see if that doesn't fix your problems.
Why isn't this in the readme.txt? Or on the outside of the package? Or in part of the troubleshooting help file? Microsoft is welcome to comment below.