Have you tried detach the mouse, whilst restart VB ?
To see if guest is saving default of host during save settings process, or a similar glitch in VB making it not save/reset.
Also the bottom right VB can attach host keyboard and mouse to guest,if you've done this on another VB may need to alter it for the test.
Clarity - I mean use menu settings of VB for detaching mouse, not unplug mouse itself , eg; you then have 2 cursors one inside the guest, and other in the host machine. Clicking in the guest join/attaches them again, so to make restart, then detach quickly, not to click inside the guest until it restarts fully etc
To see if guest is saving default of host during save settings process, or a similar glitch in VB making it not save/reset.
Also the bottom right VB can attach host keyboard and mouse to guest,if you've done this on another VB may need to alter it for the test.
Clarity - I mean use menu settings of VB for detaching mouse, not unplug mouse itself , eg; you then have 2 cursors one inside the guest, and other in the host machine. Clicking in the guest join/attaches them again, so to make restart, then detach quickly, not to click inside the guest until it restarts fully etc