I have posted this to tell you that some [rage here] person has hijacked my steam account. I cannot launch any of my steam apps, that includes US2, and somehow this [more rage here] person has managed to uninstall steam off of my computer...
Unfortunately, this happened hours after the installation of Alpha 11.2, however this wouldn't have caused the problem. I am currently working hard on the issue and hope to come back with some good news in the coming days.
---------------------------UPDATE (edited)
I don't want to go on about the actual technical things, because its quite a long story. Good news is its not a Hijacker and it was merely a software problem. Interestingly, it was an internet service provider issue, and the ISP help staff and I resolved the problems. (steam support never replied to my damn ticket)