selection key bug

I've been using Painter for more than two decades. Now it's 20\20. A couple of years ago I discovered the following problem, probably way back to Corel Painter 16, maybe earlier. From time to time, while working on an image, SELECTION icon  starts twinkling and any control of the program gets lost, except for saving the image I work with somewhere. I have no idea what causes this nasty twinkling.  Other tool icons may also twinkle, like the latest bug occurred with CLONE icon. Reloading helps, of course, but no other remedy helps. You can certainly resort to factory settings, but it's a drag when you're in the middle of working.  Anyone experienced the same? Does anyone know a remedy?