After the recent Windwos 10 Anniversary Update my Outlook started crashing upon start. So I investaged and found the .OST files to be the cause in my case. As it turns out you may delete them without problems as long as you don’t delete any .PST files. They are located under the following directory: C:\Users\<Username>\AppData\Local\Microsoft\Outlook.

Just delete the <yourEMailAdress>.ost files and try to restart Outlook again. This solved the issue for me.