"Only one Dota 2 per customer."
Alright, so I played Dota 2 for a couple of hours last night, then logged off and went to bed. Now, today, whenever I try to launch the game via Steam I get an error "Only one Dota 2 per costumer." I've tried restarting steam, verifying the game cache, etc. What's going on? I haven't tried playing the game on any other computer, or anything. Any idea?
That's appeared for me whenever there's another source game running. Open up the task manager and see if there's a hl2.exe running somewhere, or another source game. If you were able to restart Steam, none of those should have been open, but it's a place to start.