I know you may say it is nothing to do with gsx, but it is only when I try to open gsx that this happens
The problem doesn't have anything to do with GSX, and it seems related to the Windows Creator update, which has been released officially, so everybody that fully updated Windows 10, will have it by now.
However, I cannot reproduce the problem by simply opening GSX. Not in P3D 3.4, and neither in FSX or P3D 4.0 so, it must be some other addon you have installed which is affected by this.
Some users reported it only happens when using PMDG airplanes.