Check if it's the "folder view-issue". Go to "Downloads" in explorer, right click/properties and change it back to "General" instead of view as images or movies or what ever.
Same issue here. Nvidia GTX660 with Asus PB248Q. Changed to use HDMI instead. I'll wait and see if that will work. This seems to be a common concern around internet. ASUS-monitor with Nvidia display, at least on Windows 8.1