I have a number of remote sites running Ubuntu on desktop machines. Frequently, when using unattended access, I get a warning at the top of the screen stating:

"Access to remote screen is suspended while your customer is controlling the device."

this leaves me with no ability to work on the remote box. There is no customer or anyone at these sites and no-one controling the device. What is the cause and how do I resolve it. Rebooting the remote device does not resolve the issue.