I have installed cuda 7 toolkit with newest driver, and it passed all the tests, it seems that driver is loaded, but every time when I just put my laptop to sleep, and wake it up from sleep, cuda doesn't work anymore, deviceQuery
./deviceQuery Starting...
CUDA Device Query (Runtime API) version (CUDART static linking)
cudaGetDeviceCount returned 38
-> no CUDA-capable device is detected
Result = FAIL