There is a discussion on an old version of this forum that talks about this error, but I want to add what I found - I can't add to the old forum. My computer has been stable for several months. About a week or two ago I got invited to try ZumaDrive which is a cloud drive. I installed it and tried to understand it and got it figured out somewhat. Then, a few days ago I plugged in my card reader to upload a picture to Facebook. That evening, when I shut down Windows, I got my first occurrence of cardreaderlookupwindow not responding and then every time I did a shutdown or restart there it was. My card readers still work and I can "safely remove" them but the hang still occurs. The article on the old forum of "How to Fix Computers" said that any USB device or any program that looks like a USB device to Window can create this error. Uninstalling ZumaDrive fixed the problem.