session locked on mac

[JoeP]

Hi
I installed Virtrual box on my new iMac without any problems. when I create a virtual machine, everything looks fine. Then they minimize and they can't come back up. When I look at the side bar it states they are running and when I place the mouse over them it shows 'session locked'
I have attached 2 screen shots.
The first one shows that they are running, but locked. The second is when they are minimized.
It does this for both windows and ubuntu.

Thanks,
Joe