Crash during restart process after ubuntu mate 18.04 beta 2 installation

[B.]

Using Virtualbox 5.1.34_Ubuntu r121010 (see Capture du 2018-04-07 00-54-20.png)
Install Ubuntu MATE 18.04 beta 2
Follow the installation process until the restart now button is presented (see Capture du 2018-04-07 00-51-46.png)
During restart a message says a start job is running for Holds Snapp and Ubuntu live CD installer (see Capture du 2018-04-07 00-52-26.png)
After some time, the message disappears and SQASHFS error messages are presented (see Capture du 2018-04-07 00-53-24.png)

=> Virtual machine crashes and has to be forcibly restarted

After restart everything looks ok and Ubuntu MATE starts normally.

Virtual machine was allocated a 150gb virtual disk drive (dynamically allocated), a single CPU at 100%, 16 mb video memory and 3512mb RAM.