[Help] Client not working for all users?

I know it sounds crazy and I'm one for figuring out my own problems but my client doesn't seem to like select individuals computers including my laptop after everything is updated and installed you hit start game and it gives you the checking for server error. :confused:

I find it funny because a good portion of my staff can still connect using the same client....any clue on why my client is discriminating? lol

Did they update as well, or are they using the game.exe directly, perhaps?

They all updated as well. I had thought the same thing and one showed me via screen share on skype that she was updating and still she got the error.