Vbox failed to open session

[Brandon helsley]

When I start my virtual machine called openbsd it...
"Failed to open a session for the virtual machine openbsd."

>Details
AMD-V is being used by another hypervisor
Please close all other virtualization programs

Usually when this happens I issue the command kldunload vmm and that gets me past this error message. Now when I try to do this it returns with...
"kldunload: can't unload file: Device busy"

How can I unload this module? Force option does not work btw!