Hey folks, I've run into a weird and frustrating issue. I'm running an Nvidia card (GTX 1070Ti). I managed to get Gnome up and running fine. I changed the refresh rate of the video out put to 60 hz (at 4k) and everything seemed fine. When I came back to the computer after lunch the screen was blank. Restarting just goes straight into a blank screen, the screen keeps turning on then going off complaining that there's no output, as if the card is starting up and then turning off.

Anyway, I need to solve that problem so in order to try and fix things I booted into the live USB and `nixos-enter`ed the partition. I've added the nvidia proprietary drivers to see whether that makes any difference, but when I do `nixos-rebuild switch1 I get an error saying "writing to file: Operation not permitted".

So main question is: has anyone seen this `nixos-rebuild` error and have any tips on how to solve it?