I have noticed that on my machine I get a similar symptom. I have a firewall that prompts "Always Allow, "Allow Once", "Block Once", "Always Block" for each new internet connection that I make.
When I first install an Impulse game it seems to want to connect to the Impulse server to verify the licenseing. The problem is that most games are full screen so you can't see the pop-up requesting permission to access the internet. I CTL-TAB to get out of the game and then find the pop-up and click allow always and everything works after that for me.
When it does happen, ussually the cutsceens all play out and then when the main game is loading is when it freezes. Like I said for me clicking the Allow button (even allow once) seems to clear everything up so it is not really a bother.
Not sure if you are running into the exact same issue as I had, but hopefully it helps or at least gives you some ideas. Good luck.
