Unity loops on final build state

My Unity worked very well yesterday, but today Unity is stuck at the Finish phase. It builds successfully and I can play the .exe file and everything works fine there, but Unity itself gets stuck in the following image:

My task manager says Unity is not doing anything:

Reopening Unity allows me to keep coding, etc., but every time I create it, it gets stuck at Finish. Any way to fix this?

I am using Unity 5.4.1f1.