Uncommenting the Wayland line also helped me.  

I installed Fedora 28 Python Classroom on my 2010 MacBook Pro as a VirtualBox 5.2.10 guest.  After booting the screen kept jumping and the mouse moved erratically; infrequently the mouse disappeared forcing me to reboot the virtual machine.  I ran all Fedora updates.  i also updated VirtualBox to 5.2.12 a couple days ago, along with its associated Oracle Extension Pack.  None of those helped.    I also tried the regular Workstation installer, with the same results.

Graphics:  Card: InnoTek Systemberatung VirtualBox Graphics Adapter
           Display Server: x11 (X.org 119.6 ) driver: vboxvideo Resolution: 1704x1048@59.99hz
           OpenGL: renderer: llvmpipe (LLVM 6.0, 128 bits) version: 2.1 Mesa 18.0.2


I have both:
Intel HD Graphics
NVIDIA GeForce GT 330M

Thanks so much for this solution, as my Fedora 28 installation was barely usable before and quite literally gave me a headache.

Bev in TX

On May 13, 2018, at 7:43 PM, Samuel Sieb <samuel@sieb.net> wrote:


With a graphical problem, it's a good idea to include info about which graphics chipset you have.

One thing to try is edit /etc/gdm/custom.conf and uncomment the Wayland=false line.  If that doesn't work, then edit the kernel boot line and add "3" to the end of the line.  This should boot to a console.  If that works, then login as your user and try running "startx".
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