Currently, I am running VMware ESXi 4.1 on a test system. To manage ESXi, you need the VSphere client, which is only available for the Windows platform. Therefore, I run VMware Fusion on my Mac to be able to access VSphere and manage my ESXi host.
The trouble is that both ESXi and VMware Fusion use the control-alt shortcut to release a console. So as soon as you start using a console within the VSphere client which itself runs within VMware Fusion, you cannot get back to the Windows OS.
You will have either access to Mac OS X or the ESXi guest. And to top it of, the mouse just completely disappears on Windows.
To get arount this problem, you need to somehow be able to send a control-alt sequence to the Windows guest withouth actually pressing control-alt.
Fortunately, VMware fusion allows you to create a key mapping that allows this.
Within the preferance pane, the first tab is called Key Mappings. You can create a new key mapping. For example, I mapped control+q to control-alt. This allows me to get out of the ESXi guest within the VSphere client, witouth getting grown back to Mac OS X. As a side effect, the mouse also showed up again, which is to be expected.