The error messgae might be caused due to CUDA drivers. Do you have the latest drivers installed? If not, install the latest drivers and verify if you still see the error message.
You can get the drivers from: http://www.nvidia.com/Download/index.aspx
This may also arise due to permissions related issue, therefore try starting the matlab session as root or sudo user.
You can also refer GPU CUDA problems: CUDA_ERROR_UNKNOWN - MATLAB Answers - MATLAB Central (mathworks.com) , it discusses some other ways that might solve this issue.
