T3RR0R15T: I don't think the grenade thing would crash. If there's no client, or the client is dead, it won't track him.
The "new version" message is just there to encourage people to upgrade when it's not forced. I think there's like a 30% chance of seeing it.
blaa: Anti-cheat stuff, mostly, and technically all builds are tests.
lester: Sounds like your network traffic is somehow being corrupted when downloading a file. I've not had that issue installing a fresh copy of the game and downloading stuff off of servers. Also, the download code has not changed for several builds. I suspect the issue lies in your network adapter, router, firewall, or ISP.
Full install is up on the first post - please test it out.