Sometimes it happened, try again after few time probably it will work smoothly.

@joinski that's a mix of kernel version + nvidia drivers version

@acris i did, didn't appear to make much difference....

@substring That link gives me a 404 error, I assume I would have to have the recalbox running 4.1 for it to work? I went back to 4.01 because it works great still, and because it takes many hours to load roms after doing a clean install I won't be trying 4.1 again until I get a new raspberry pi. 4.1 works fine on a friend's RP3, so I'm going to try and upgrade to one of those for christmas.