Same problem. After a bunch of updates were installed, Windows boots but most of applications fail to start with 0xc0000005 error.
The updates installed on this day were mostly "Security update for Microsoft Windows", one "Update for Microsoft Windows" and a bunch of .NET framework updates which I assume must be unrelated (.NET is not system-level stuff).
Additionally one of the updates (Cumulative update for IE) failed to install at boot time, switching to "Rolling back update" and then rebooting.
Which apps work:
Notepad works, explorer works, cmd.exe works, iexplore.exe pops up a window but crashes. Most of 3rd party apps do not work, even unassuming ones such as a simple dictionary app. Some third party services (skype update) do not start, although I don't know if with the same error or not.
Event logs show mostly nothing unusual, at least no blatant differences with normal boot process and no additional errors with the exception of "SkypeUpdate failed to start" and the likes.
The problem is temporarily suppressed by:
1. Disabling Windows Update service (Start mode: disabled) and telling Windows Defender to shut up about it.
2. Going to "Add and remove programs -> Updates" and uninstalling updates which were installed the last day.
But how can we solve this permanently?