I got this on three different boards. (DP45SG, DX58SO and another board)
Some extreme cases where after installation of the chipset driver the usb mouse and keyboard fails to work.
- re-install the windows
- update the service pack.
- install lan driver.
- update the windows.
- then install the rest of the drivers from the website directly.
Possibly for you as well, it will be fixed like mine.
All the best,