Is "MenuTab" the name of the servlet AND the name of your context? If so, your URL should be "http://localhost:8080/MenuTab/MenuTab", but I suspect your context is something else entirely in which case it should be "http://localhost:8080/<context>/MenuTab".
"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." -- Ted Nelson