After the recent (10 Dec 2014) automatic Microsoft Office update,
the cached control type libraries (extender files, *.exd) may be out of sync. To resolve this issue, you must delete the cached versions of the control type libraries (extender files) on the client computer.
Solution:
All *.exd files must be deleted; they will be re-generated automatically the next time Office needs them.
To do this, first, close all Office applications, and then either:
Put this in a batch file (a text file with extension .bat) and execute it.
del %temp%\vbe\*.exd
del %temp%\excel8.0\*.exd
del %appdata%\microsoft\forms\*.exd
del %appdata%\microsoft\local\*.exd
del %temp%\word8.0\*.exd
del %temp%\PPT11.0\*.exd
Or, alternatively, search your hard drive for files named *.exd and delete them all — though if you happen to have unrelated files with an .exd filename extension, be careful not to accidentally delete those!
Source: TechNet.com
