did you remove the resource.cfg file as well? I had a similiar problem when installing AM AFTER WA was already installed. It would bring up the loading screen and then not go any further. The solution I used was first read all the threads you can in the sticky section which lead me to the following:

Go to Program Files/Electronic Arts/The Sims -> copy the resource.cfg file PASTE it in the Program Files/Electronic Arts/World Adventures/ directory
In the World Adventures directory create a directory called Mods and within the Mods folder create a folder called Files
Copy the files within Program Files/Electronic Arts/The Sims/Mods/Files to the newly created directory within World Adventures
Copy the file d3dx9_31.dll from Program Files/Electronic Arts/The Sims/Game/Bin to Program Files/Electronic Arts/The Sims World Adventures/Game/Bin
Then go to My Documents/Electronic Arts/The Sims 3/ and delect scriptCache.package
Load Game

Profit

That's basically just saying what has already been stated, but as this is my first post I figured I would be as detailed as possible.