here is your answer
Quote Originally Posted by Dawnseeker View Post
This happens when the number of coins your client think you have is different from the server. There are a number of things that can cause this (Cheat Engine, rapidly clicking on some rewards, etc), but the server number is correct and is not susceptible to these problems. So when it sees a difference there, normally when you're trying to buy something, it disconnects you to resynchronize your client with the server.