New boot camp install of win7 64bit, mouse and keyboard not recognised

I have just purchased a 27" imac (2012 model), and installation of boot camp which i have done dozens of times before, is now causing a weird problem.

I had to install windows 7 from USB this time, i only have a 4gb usb so i installed windows 7 from that, and did 'windows support' separately on another 2gb stick.

Installation of win7 was smooth, no problems occurred until after everything was installed and i went to install the boot camp drivers (which were downloaded for me by the boot camp assistant) they weren't put onto my usb stick, instead the files went into my user folder and it took me a while to find them and drag them onto the blank usb stick.

Once i did this i rebooted into windows and ran the setup.exe in the folder.

It ran its course and installed what it needed too, prompting me to reboot which i did.

After rebooting it was now showing the login screen at full resolution on my display...but my mouse and keyboard were totally unresponsive.

No lights, movement of the mouse, the optical light is off etc etc

i plugged in 2 other wired keyboards and mice...nothing.

I cannot login unless i boot up in safe mode, but in safe mode when i check the device manager list, it says everything is fine and there are no red crosses or warnings by any of the devices.

I'm really stuck and don't know what has happened, it seems the usb ports do nothing under windows, it all works fine under MacOSX.

Help!