First you need to do some reading;
1) FlyOrDie Online Games FAQ
http://www.flyordie.com/games/help/support/contents.html
2) How to clear your cache?
http://www.flyordie.com/games/help/support/clearcache.html
3) Also you 'may' want to manually delete files from the java cache.
4) You should try different browsers with clean profiles. Create a new user login for your Operating System (Windows) and try to login from there.
There are some bugs currently with this site's javascript. Hopefully it will get sorted out soon.
5) Search this forum for this same question and the answers supplied recently.
http://www.google.com/search?q=site:forum.flyordie.com
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goodday