
I'm on my MacbookPro and using TeamViewer for remote access to my 2k3 Server. On this server I installed VirtualBox to create a virtual machine. But now I stuck at this screen and no more can use my mouse.
How can I release the mouse capture?

I'm on my MacbookPro and using TeamViewer for remote access to my 2k3 Server. On this server I installed VirtualBox to create a virtual machine. But now I stuck at this screen and no more can use my mouse.
How can I release the mouse capture?
You need to press "host key" which is written in right bottom corner of VirtualBox window.
Looking at your screenshot its Right Ctrl.
Its not default Mac Command ⌘ because you are running VirtualBox on Windows host, which you are accessing using TeamViewer.
See virtualBox manual: link
Press Control+Command+⌘ at the same time to release the mouse from the VirtualBox window.
You could also try triggering Sticky Keys (Press Shift repeatedly) that will pop you back to windows control. click no on the Sticky keys popup before you click back into virtual box (You can't trigger sticky keys if the pop up is open).
You also use Ctrl+Alt+Del per Teamviewer Panel.
If you look closely at the image below it shows the hotkey that needs to keep on pressing to escape from the virtual machine.
I have faced the same issue while I installed virtualbox for the first time.
To switch between host and the VB press "right ctrl" on your keyboard.
Hope this will solve your problem.
Already Virtualbox gives you the guide at the bootom right of the window:

for me, as you can see in the picture, i have to use the Command button (⌘) LEFT one.