Mavrothal - Many thanks for your quick reply and successful solution

Your diagnosis was correct and the xrandr pet solved the issue

My 71 year old eyes can now relax a little

I have no idea if the resolution problem is a bug in Slacko or just something fickle with my hardware

Again - Thanks

algol 68 reported similar issue Nov 20 2015. I changed resolution at startup from 1920x1080 to 1024x768. This is accepted and it runs fine for only a very short time till it reverts back to the original 1920x1080. The machine is a brand new ECS Liva with Intel Bay-Trail Celeron N2808. Slacko 6.3.0 ...