White line in WMC in 4K at 60hz

[pnag]

Evening, all,

I'm at my wits end here - I've tried the registry hack (logical width dropped by a pixel) but the white line at the right hand side of the screen persists; I thought I had seen someone posting about permissions that had to be set for it to stick as well? Can't find it now though.

Can anyone help? I'm so close, but the blasted white line keeps coming back!