I'm going blind - I looked for a BIOS update and didn't find one. However after updating my BIOS the problem still occurs: switching between two user sessions results in a black screen. If anything the problem is worse - much easier to duplicate as it now only takes a few switches to trigger this bug now.
As per your request I ran: sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date. The output of these commands is: A12 02/18/2014 Marking this report as Status New. ** Changed in: xorg (Ubuntu) Status: Incomplete => New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1437557 Title: [Dell Vostro 3550] Black screen on user switch. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1437557/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs