You need to check your computer for malware. If you can't do it yourself, you'll need to have someone do it for you. Is there a computer repair shop near you? You'd need to tell them the symptoms -- and that you think malware is blocking you from being able to log into Big Fish.
They let me in 1 time each, then not again.
That's what happens when you're infected with a virus -- and the virus infects every program that you run. Firefox and Opera worked right the first time because they hadn't been infected yet. After you ran them, they became infected and wouldn't run properly any more.
You need to get this cleaned up, and I don't think we can do it from here. Someone has to run scans on your computer and determine whether the virus/malware can be removed or not.