Vive error 109

About 6 months ago I packed my vive headset away as it was getting the in way. I removed the link box from the side of my PC and installed a second monitor.

I set my PC up to run 2 monitors in the Nvidia control panel.

Fancied having a go on the vive this weekend so set it back up.

Removed one of the cables to the second monitor.

Plugged the link box back in. Went into Nvidia CP and removed the second screen.

However when I start steam VR I get error 109.

The desktop is showing in the headset too.

I have tried uninstalling steam VR thats not helped.

I have a feeling its to do with Nvidia but I am clueless.

The vive is plugged into the same port its always been plugged into. (DP).

Monitor is on the same HDMI as normal.

Anyone got any ideas?

Plugged the second screen back in and moved the vive to another port and it works now... <shrugs>