It looks like this bug was reported before the official release of 18.04. Can you please update the system and tell us if the bug still occurs?
** Package changed: xorg (Ubuntu) => ubuntu ** Changed in: ubuntu Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1759916 Title: black screen after logon To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/1759916/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp