Messenger: Mac Return problem?

Hey guys this just started yesterday and basically the problem is when I hit return to send a message I can't type again straight away. . .I need to now click the dialogue box to type.

Failure to do so makes a noise and it won't let me type until I click the dialogue box.

Does anyone know what's wrong? . . .It's a pain having to click the box after every message.

Thanks in advance.

 

Thanks for that. . . a member of three years. . .you'd think I would learn to search.