This is weird.
I was just checking some stuff on local, and all links in all admin menus are totally fine except for the link to ?action=admin;area=smileys and any sub-areas under that. Any of those links causes a server error.
Ok, so what is special about the menu link to the smileys section of admin? Why would that one apparently cause Apache to flip out, while no other links on the site have any problems?
And no, there are no errors in the forum error log.
ETA: Apache error log shows this:
[Tue Jun 07 17:53:30 2016] [notice] Parent: child process exited with status 3221225477 -- Restarting.
[Tue Jun 07 17:53:30 2016] [notice] Apache/2.2.22 (Win32) PHP/5.3.10 configured -- resuming normal operations
[Tue Jun 07 17:53:30 2016] [notice] Server built: Jan 28 2012 11:16:39
[Tue Jun 07 17:53:30 2016] [notice] Parent: Created child process 2832
[Tue Jun 07 17:53:30 2016] [notice] Child 2832: Child process is running
[Tue Jun 07 17:53:30 2016] [notice] Child 2832: Acquired the start mutex.
[Tue Jun 07 17:53:30 2016] [notice] Child 2832: Starting 64 worker threads.
[Tue Jun 07 17:53:30 2016] [notice] Child 2832: Starting thread to listen on port 80.
[Tue Jun 07 17:53:46 2016] [notice] Parent: child process exited with status 3221225477 -- Restarting.
[Tue Jun 07 17:53:46 2016] [notice] Apache/2.2.22 (Win32) PHP/5.3.10 configured -- resuming normal operations
[Tue Jun 07 17:53:46 2016] [notice] Server built: Jan 28 2012 11:16:39
[Tue Jun 07 17:53:46 2016] [notice] Parent: Created child process 6196
[Tue Jun 07 17:53:46 2016] [notice] Child 6196: Child process is running
[Tue Jun 07 17:53:46 2016] [notice] Child 6196: Acquired the start mutex.
[Tue Jun 07 17:53:46 2016] [notice] Child 6196: Starting 64 worker threads.
[Tue Jun 07 17:53:46 2016] [notice] Child 6196: Starting thread to listen on port 80.
[Tue Jun 07 17:56:40 2016] [notice] Parent: child process exited with status 3221225477 -- Restarting.
[Tue Jun 07 17:56:40 2016] [notice] Apache/2.2.22 (Win32) PHP/5.3.10 configured -- resuming normal operations
[Tue Jun 07 17:56:40 2016] [notice] Server built: Jan 28 2012 11:16:39
[Tue Jun 07 17:56:40 2016] [notice] Parent: Created child process 2768
[Tue Jun 07 17:56:40 2016] [notice] Child 2768: Child process is running
[Tue Jun 07 17:56:40 2016] [notice] Child 2768: Acquired the start mutex.
[Tue Jun 07 17:56:40 2016] [notice] Child 2768: Starting 64 worker threads.
[Tue Jun 07 17:56:40 2016] [notice] Child 2768: Starting thread to listen on port 80.