I get this popup while trying to use the windows 8 assistant to see if my laptop running windows xp can be upgraded to windows 8. There are no external devices.
Sorry that was meant to be a comment on another question about “a device connected to the system is not performing…” Pop up
While the error indicates that there is a problem with an external device (such as a USB flash or external hard drive), some users said that the error "A device attached to the system is not functioning" or "A device connected to the system is not performing" occurs when no external devices are connected.
It is a common issue and can be caused by a variety of different reasons, including the corrupt system files, faulty Windows updates, malware infections, etc.
To fix "A device attached to the system is not functioning" or "A device connected to the system is not performing" error, you can follow steps provided in this guide.