Hello mpruffin
My first act would be to download the ISO again (Torrent), run the checksum, transfer to usb or dvd installation medium and do a fresh install.
If the problem persists come back again. I am not a technical expert, but our community has a lot of knowledgable people. 
EDIT (02.04.2019)
This post UM 18.04.2 logs out instead of suspend and destroys unsaved documents
says that 18.04.1 and 18.04.2 have different kernels. It may be worth trying 18.04.1.