On Monday Microsoft released KB 2956149, a completely new patch whose sole purpose is to undo the damage caused by this month's Black Tuesday patch KB 2920732.
As described in the KB article, this new patch does the following:
... fixes the issue in Microsoft Office Home and Student 2013 RT in which you cannot start PowerPoint 2013 and you receive the following error message after you install update KB 2920732:
C:\Program Files\Microsoft Office\Office15\1033\PPINTL.DLL is either not designed to run on Windows or it contains an error. Try installing the program again using the original installation media or contact your system administrator or the software vendor for support. Error status 0xc0000428.
Those of you who have PowerPoint RT installed and were unfortunate enough to have Windows Update enabled last Tuesday likely woke up to discover that PowerPoint RT didn't work. Now, a week later, PowerPoint should start working again.
Windows RT users can't turn off Windows Update -- if you connect to the Internet, you automatically get the latest patches installed. Let's hope that design decision doesn't spread.