Unfortunately, the latest patch from Valve "Love and War" has been crashing clients for still unknown reasons.There's not much we can do server-side at the moment, except maybe disabling the new taunts, see if that helps.
These en-masse clients crashes have been reported by other server ops, so it's not a problem specific to our servers. We've seen these kind of clients crashes in the past, especially when new items were introduced, weapons with "strange new" abilities and taunts.
When these en-masse clients crashes occur, the server usually stays online, but a map change is required to stop these from happening over and over again.
Hopefully, Valve will figure out the issue and release another patch soon.