Failed to attach the USB device USB2.0 WLAN Adapter [0200] to the virtual machine Backtrack 4 R2.

USB device 'USB2.0 WLAN Adapter' with UUID {8be14ae9-0542-4dc6-a9ef-6ab00d254c0c} is busy with a previous request. Please try again later.

Result Code: E_INVALIDARG (0x80070057)
Component: HostUSBDevice
Interface: IHostUSBDevice {173b4b44-d268-4334-a00d-b6521c9a740a}
Callee: IConsole {1968b7d3-e3bf-4ceb-99e0-cb7c913317bb}
I downloaded Backtrack 5 R2 and i saw this problem, and i don't remember it in Backtrack 4 R2 so i downloaded and had the same problem...

Can anyone help me understand the problem... (I'm using VM VirtualBox)

I apologize for my bad or unprofessional English.

[Any reply is appreciated.]