Wanadoo Livebox help needed!

I conected my macbook pro to it all fine and it was working all ok but since friday sometimes the conection will go and it says it cant conect to the livebox i have to click on the airport symbol at top of screen select other (even though my livebox is there) i have to enter the name and the WEP code and then it works but sometimes it still cuts out. What can i do? Its not just simple loosing conection its the actual conection saying its conected to the box but no internet works untill i re conect.