The blue popup info bubbles change the texturing grid overlay from a grid to an white opaque texture with a transparent rectangle that has the texturing crosshair in its middle. The transparent rectangle is exaclty as wide and high as one texture repeat. The popup info bubbles that provoke this behaviour on my computer are friend list changes (online/offline notifications) and inventory changes (like eg. notecard transfers). For some reason the sales information popup does not change the texturing grid. The bug only occurs when the friend list change happens while you are editing the texture(s) on a prim ("Select Texture" is active). When you are not editing a texture, the texture crosshair overlay is not affected by the blue popup windows. It doesn't matter if a single texture or all textures on the prim are selected. I have tried both the current 169.21 as well as the 169.44 nvidia beta drivers - both produce this issue. This copy of Windows has been installed about a month ago; I'm using it under a limited user account but the issue also persists when I log on as administrator.