Windo/Full Screen

So my league client is seemingly randomly changing my windowed mode to "Windowed" from "Full Screen". When that happens I cannot use abilities nor can I hit escape to bring up options. I have to alt-tab and close league to restart it manually. This is a new thing, (it was happening on patch 5.6, just much more rarely). Has anyone else run into this problem or anything like it or have any suggestions?