I have ArcGIS 10.5.1 (student evaluation version) this same issue happened on my previous 10.3 version so I uninstalled it an upgraded to 10.5.1. Everything was fine for a week or so but then it started happening again. Whenever I try to save my work in ArcMap it crashes and closes, losing everything. It even does this on blank maps I open up and try to save. Please help :-( I have a lot of homework I'm falling behind on.