There's a possibility your client's corrupted. Try repairing it from the login screen.
Had that kind of issue once persistently and that was it that time. Every once in a while the client coughs up blood and chokes on me, but it's never something this consistent.
Alternatively if you're leaking memory, the game will fail to connect just due to your computer refusing to open the game. That's another thing you can check as well from task manager - if your RAM usage is through the roof with nothing opened, you should look into that as well.