Applications and utilities are corrupt after update to 10.13.1
I have recently applied the 10.13.1 update and some weird stuff has happened. Some of the applications and utilities bundled with the Mac OS in those folders are corrupt. Looking at the package info, it looks like some of the resources are missing.
I also have an external drive that has a 10.13 install (no update yet). It still has "good" copies of some of those applications and utilities. Unfortunately I can't copy those over because when I try, I get a message that "(App Name) can't be modified or deleted because it is required by macOS".
Any way to fix this, short of reinstalling everything? And any idea why this may have happened? It's only apps and utilities bundled with the OS, and not all of them.
Mac mini, macOS High Sierra (10.13.1), Late 2012 Mini (quad core i7)