Unknown error in IBuilder::buildCudaEngine call


Occasionally I am getting this error

c:\p4sw\sw\gpgpu\MachineLearning\DIT\release.1\builder\cudnnBuilderUtils.cpp (247) - Cuda Error in nvinfer1::cudnn::findFastestTactic: 999 (unknown error)

when calling

engine = builder->buildCudaEngine(*network)

I wonder if anyone can give any ideas what it means or why it could happen.

This is on Windows 10 with TensorRT 5.1 GA on GTX 1050 driver 425.25
Same program works fine on Ubuntu and Windows with different GPU cards.