I assume you have been experencing this error recently and you can access the game using the browser? Assuming you haven't installed any security software recently, try this

1.install the latest version of mini client if you have been using the old one..old one is very buggy

2.flush dns

3.install the latest version of flash

4. Re install the mini client

I have personally experience this few times,typically it loads in a while or have to reopen the client.