How to close an app?!

[Dishmonkey]

Wow is this driving me crazy. Sometimes it appear my Rift gets itself totally confused when believing an app is open.

I try to launch something but Oculus tells me I have to close another app.

Is there an indicator somewhere of which app may be running?

Even when I have completely closed Oculus and restarted it still tells me this.

The only method I have at the moment is a ridiculous complete reboot of my PC.