Any application that uses Command + S as shortcut, does not work. It's very weird, I'll give it a shot on another user account.
Then the OP hasn't found it.I think some other app is capturing Cmd+S as a global keyboard shortcut, so it doesn't get sent to the app you want to.
I just created a new account and the commands work just fine.
What he said. And if pulling the plist files doesn't do it, you'll spend about the same amount of time switching to a new account as you would continuing to guess at other causes. The former will fix it, the latter might not. Deleting an account produces an option to save your key files from that account so you can import them into a new one.If it works on another account, it's something in your user directory. I recommend pulling com.apple.systempreferences.plist and com.apple.universalaccess.plist from /Users/(yourname)/Library/Preferences to the Trash, and then doing the restart.
I think some other app is capturing Cmd+S as a global keyboard shortcut, so it doesn't get sent to the app you want to.