First I would shutdown the computer remove the board, boot the computer once without any hardware connected, then shutdown again and plug in the board again into a different slot if possible. If this does not help, try the board in another computer. If the board still does not work even in the second compuiter, call your local NI office, the board might be damaged and needs a repair.
If the board works in the second computer, reinstall the driver on your original computer, or download and install thwe latest driver version.