log on pop up even though it sends and recives email

I reciently downloaded and setup eM Client. I have it on several machines and I like it. I just set it up at work and I have an issue. Every time it logs onto my server it pops up telling me that the surver says unatherised and wants me to retype my password. It never shows that it loggs on to the server, However it sends and recives just fine. How can I get rid of the pop up?

how many accounts do you have created? Could you send me a screenshot of the error message?