“Save As” causes Office to crash

Since recently, when doing a "Save as" in the following Microsoft Office 2013 applications, they crash:

• Word 2013
• Excel 2013
• PowerPoint 2013

The crash immediately quits the application with the usual dialog box (in German):

When looking at the Windows Event Log, there is this entry:

Source: Application Error
Event ID: 1000

Name of the faulty application: WINWORD.EXE,
Version: 15.0.4631.1000,
Timestamp: 0x5396ad5c
Name of the faulty module: mso.dll,
Version: 15.0.4631.1000,
Time stamp: 0x5396b083
Exception code: 0xc0000005
Error Offset: 0x00003abc
ID of the faulty process: 0x3038

Start time of faulty application: 0x01cfa4a622f788c6
Path of the faulty application: C: \ PROGRA ~ 2 \ MICROS ~ 1 \ Office15 \ WINWORD.EXE
Path of the faulty module: C:\Program Files (x86)\Common Files\Microsoft Shared\Office15\mso.dll
Report ID: 63868999-1099-11E4-bee7-00224d87b4fd
Full name of the defective package:
Application ID, which is relative to the defective package:

This error only happens during Save as. It does not happen during Save or Export. In addition, Microsoft Office Access does not crash at all for the "Save as" operation.

I've already uninstalled several things that I have recently installed which might influence Office. Since I'm a developer it might also be some recent update to Visual Studio 2013 which I cannot uninstall if I want to stay productive.

My question:

Any hints on what might cause this error and/or how to solve it and/or how to further investigate the actual cause?

Update 1:

Just did an Office Repair and a reboot with no improvement.

Update 2:

I've attached the Visual Studio debugger to Winword.exe and let it stop on exceptions. It stopped as excpected but unfortunately, neither the call stack nor the disassembly shows something valuable.

Update 3:

When clicking the "Close application" button at the end of the Windows Error Reporting dialog, it redirects me to this Microsoft Knowledge Base article:

"Office 2013 programs crash when using the File tab (Backstage) and the July 8, 2014 update is installed"

This seems to be the solution (Currently they recommend to uninstall the update KB2880987).

Update 4:

The Microsoft Knowledge Base article did not help. Still crashing. What actually did help was the suggestion by dyker to delete this registry key:

HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Common\Identity\Identities

(Actually I just renamed it to "_Identities" in case something might go wrong).

Update 5:

The suggestion to delete the "Identities" registry key worked one-time. Next time trying to save as, the error appears again :-/

Update 6:

Microsoft now updated their Knowledge Base article with the information that a fix is available either via Windows Update or as a direct download.

This fix worked for me.