It generally is caused by buggy graphics drivers. You may be able to find more information if you press F12 and look in the browser console. Usually the browser will then revert to software rendering - this message only appears if it also failed to revert to software rendering as well, which is a particularly serious (and also rare) problem. Make sure any software updates are installed for the system and browser, and that the graphics driver is up-to-date. You could also try a different browser.