I had SourceTree v2.3.1 installed (Windows 10 64bit)
For some reason it stopped working this morning - click on .exe wouldn't open and Event Viewer shows errors.
I uninstalled it, downloaded the latest version and tried installing it. In the install process, I get to the "Altassian Account" step, a new pop-up shows but is empty (image below)

So basically, can't install SourceTree. Me needs help