This happened a couple months ago when the game was patched, but took a bit longer to affect the game than it does now.
Client looks like it’s loading fine, gets past the “Client Ready” phase of loading, and then just kicks you back to the main menu with “invalid packet error” listed in the console. I’m guessing this (along with the other game breaking bugs) is why the servers are so low pop this weekend. Couple this bug with the fact that you need to relog out of the game to access your boxes after using them once, and it’s a real pain in the ass… even if you do happen to get by the bug when logging in (which I haven’t been able to yet, in 10+ tries) , you will have to relog at some point anyway.
I’ve only played on the Washington server since the update but I’m guessing it’s happening on others too.
Please vote this up (using the link above) if you’re encountering this problem so we can get a fix ASAP!