Everyone's forced to re-download and re-install the entire game.. so u need the 870MB client.. not just a launcher.
1. Download the client from
HERE
2. Uninstall Fiesta (I just went to add/remove programs, and removed Fiesta and Fiesta Launcher)
3. RESTART YOUR COMPUTER
4. Run the client that you've d/led... wait about half an hr -.- And.. it should install properly...
3.