virtualbox.org

Host: Windows 7 SP1 64bit VirtualBox 4.1.2
Guest: Windows XP Pro SP3 32bit, clean install, default VirtualBox options except 512MB RAM, using VT-x acceleration

If I open a command prompt, it opens in a window and works normally. I can press Alt-Enter to change the command prompt window to full screen and that also works normally. However, if I press Alt-Enter again to return the command prompt to a window the virtual machine hangs with a black screen. It then either remains frozen so I need to power off the virtual machine or reboots after a few seconds.

This problem only happens if the guest additions are installed.

The same issue is present under Windows NT 4.0, Windows 2000, Windows Server 2003 R2 32bit, and Windows 7 32bit.
64bit Windows systems are not affected because they cannot display a full screen command prompt.

If this behaviour is completely repeatable then you would be better off opening a bugtracker account and posting an official bug report. The devteam reads those, they don't always read the user forums. Unfortunately, and confusing as it may appear, the account needed for the bugtracker site is separate from the one you need for these forums.

This behavior is 100% repeatable for me on Virtualbox 4.1.2 whenever the 4.1.2 guest additions are installed. I haven't tested other versions. I created a bug report at http://www.virtualbox.org/ticket/9636

It would be helpful if someone else with a Windows XP 32bit guest and ideally a Windows 7 64 bit host could test whether they also have this issue.