Applescript fails with error (-600) when launched over ssh on Mavericks

Application isn’t running(-600) is an operating system error.

An operating system error is an error that occurs when AppleScript or an application requests services from the Mac OS. They are rare, and often there is nothing you can do about them in a script, other than report them.

Arrrrgh! I don't want this to be the answer, but after trying just about everything, this now seems to be working after a restart.... My guess is that something in appleeventsd got confused (although restarting just appleeventsd on its own didn't fix anything). After a restart osascript seems to be behaving again. I'm still not convinced this is fully fixed, but it does seem to be working for the moment...