Zombie Panic: Source, Invalid Steam UserID Ticket?

[Korten12]

So I tried to play ZP:S and for some reason no servers came up so I decided to reinstall it and now the servers popup but I get disconnected with an error saying: Invalid Steam UserID Ticket.

Anyone know how to fix this?

 

[TheGreekDollmaker]

Go to the official Zombie Panic Source Forums and ask there.

I am a member too but i have no idea how to solve this.