As far as I could test it, the problem exists with any combination of host and guest.
There are quite a few similar posts all over the web, but mostly related to much older versions of VB.
I can reproduce the problem anytime, with a variety of hardware, from an old PentiumD without VT up to an I7 with internal GPU, in almost any version of VB including the latest 4.1.2 and with almost any combination of OS for host and guest.
I have 2 Monitors, both set to 1920x1200.
I setup a guest in fullscreen mode to use monitor 2.
I install some kind of application (a game) that runs fullscreen within the guest in a resolution different from the host monitor.
If it wasn´t a VM, the OS would switch the screen resolution to match the requirement of the application.
VB displays the guest with a huge black frame around, meaning it switches the window size instead of the screen resolution.
When closing the application, the OS attempts to restore the original resolution.
VB will remove the black frame instead.
With 2D accelleration disabled this works fine, but with 2D accelleration enabled, the guest freezes upon restoring the resolution.