Excel 2013 not starting properly

At our office we all work with Office 2013. Today one of our employees was unable to start Excel. It seems that the program does start, but only shows a very limited screen:

I am unable to minimize, maximize, resize, close or even move the window. The only way to shut it down is to stop the EXCEL process with task manager.

I've already tried the following:

• Repairing the installation of Excel
• Uninstalling and reinstalling Excel
• Starting Excel in save mode, (which does work) and then disabling any and all Add-ins
• Installing every possible update for Windows and Office
• Ruing as Admin (although the user already is local admin on this pc)

When logging on as a different user, it works without problems. Also, other Office programs, like Outlook or Word have no problems at all.

Is there anything else I can try?

I know how to remove the local profile of the user, should the problem be a corrupt local profile, but I'd prefer to keep this a last resort, since this would cause me to reconfigure a lot of settings.

Note: the OS is Windows 7 Pro x64