Ixix, I may have identified an event when Avalon drops its Global Highlights.plist. Since last night there have been a few game crashes. There are different results when attempting to connect when the game is down. Most of them are variations on a short server-side message, but the one that drops the plist file is when the the following dialog comes up:

Error Connecting
Sorry, an error occured while attempting to connect. You'll need to quit and attempt to sign on again. If the problem persists, the game might be down or your internet connection might be disrupted.

I'm guessing this indicates nothing was returned from the game server, but the account was authorized via the authorization server. When this dialog appears, the game window itself doesn't open, and anything associated with the game window opening/closing may not be happening correctly. I didn't check to see if the plist was missing after Avalon closed, but I think it may be dropping the file and creating it from scratch on the next login attempt. It's pretty consistent. If I have another opportunity I'll check to see when the file changes.