No wireless keyboard or mouse after using bootcamp in Mountain Lion

Hi there,

I had BootCamp installed on my iMac late 2009 under Lion using Windows 7 64bit without any issues. Since upgrading to Mountain Lion I've noticed that if I boot into Windows using BootCamp, the next time I boot back into Mountain Lion I have no wireless keyboard or magic mouse and am stuck at the login screen! The only thing I can do is switch my iMac off and then kill the power at the socket for 10 seconds, switch it back on and that resolves it. I've tried updating the Windows Support Software from the BootCamp assistant but this hasn't resolved my problem. This is a real pain as I have no usb keyboard and don't want to continue switching off my iMac by holding the power button down in fear of messing up OSX.

Has anyone else come across this problem and if so have you managed to resolve it?

Many thanks,

Andy.