Earlier today I was having some connection issues. I'd black out when loading and I'd have to quit SK and restart. Mentioned it to the friend I was going to run with and he stated he had had the same problem earlier. I got the issue again a while later, and then my client said that the game is being updated and I should try again in a few minutes. This was in the SK client, the patcher didn't show up or anything.
Now I'm able to log on again, so this seems rather inconsistent.
Same here. Happens every once in a while after trying to load a mission. Yesterday got it after 50 speed runs through Alone in he Dark mission (thanks Kataclysm), today after 15 runs and then again just one attempt later. Black screen, closing the window, re-openning and [this] pops-up. I have to wait anywhere from 5-10 minutes before being able to play again.
//EDIT: Using Steam, if that's any help. 5 minutes of being unable to login for 5 minutes of playing, awesome.