CUDA 10.0 breaking Kubuntu 18.04 LTS

Hoping you can help me with something. I really like Kubuntu but when I install CUDA (10.0) and CuDNN (7.6.2), it breaks my installation of Kubuntu. By that, I mean I get a terminal error and then it reboots to a tty1 login screen. I can get to the GUI by running startx but then I can’t use my keyboard or mouse (both wired USB). I reinstalled Kubuntu and tried again but got the same result. For info, I used the Kubuntu GUI to install the nVidia driver (435, iirc). Has anyone else come across this issue and know how to make it work? In the meantime, I’ve resorted to using Ubuntu 18.04 and CUDA works fine on it.

EDIT: I modified the instructions from this tutorial to install CUDA, CuDNN