nvidia-smi error: Failed to initialize NVML: Unknoown Error

I got “Failed to initialzie NVML: Unknown Error” on our TESLA box when trying to run nvidia-smi command. The server has one GeForce CTX TITAN GPU card and 2 Tesla K20c cards.

The driver version for the GeForce Card is: GeForce 344.11
The driver version for the K20c cards is: 340.62

The OS is Windows 2008 Server.

Please help.