When a game starts that I am participating in, Spring freezes at "Connecting to Server". The only way to get out of it restarting your computer, which is a pain in the ass itself. And of course, it keeps you from actually getting into the game, so I consider this bug pretty major.
Reproducabiltity=Always.
EDIT:God...this is a bad day for me.

Yah, I fixed this one to, turns out my firewall was messing it up. Me=Spammer.