Tonight (all of a sudden): I started having the following issue:
Whenever I go to ANY project in Unity (including a new one) and try to run the project I get the following exception:
NullReferenceException: Object reference not set to an instance of an object UnityEditor.ObjectSelector.OnDisable () (at C:/BuildAgent/work/6bc5f79e0a4296d6/Editor/Mono/ObjectSelector.cs:138)
If I try to click any of the property window attributes that bring up a dialog box to browse for objects then the entire Unity3D application crashes. This happens every time for every project. It was fine earlier today. I have uninstalled-reinstalled unity multiple times (I made sure that the folder was deleted in between and I tried different install locations).