Comment 14 for bug 1658996

I have the same issue of a blank all white Welcome screen when installing Ubuntu Mate 17.04 on VirtualBox 5.1.20 on both my laptop and desktop. The Welcome screen is visible at first but as soon as I install the guest additions that let me use full screen mode the Welcome screen and Software Boutique stop working and are just all white windows.

The laptop is a 2.8GHz core i5, 8 GB of RAM, 1920 x 1080 15" monitor, intel HD Graphics 4600 & Nvidia GTX 860M. The desktop is a 3.4GHZ core i7, 16 GB RAM, 1920 x 1080 monitor, Radeon HD 6970 graphics card.

I had no luck trying
sudo apt-get remove ubuntu-mate-welcome
sudo apt-get install ubuntu-mate-welcome

Trying Ubuntu Mate 16.10 in Virtualbox on the laptop results in the same issue once the guest additions are installed to allow full screen mode.