In order for it to come up when you type in your URL, you must rename intro.html to index.html. And, of course, before you do that: index.html to SomethingElse.html.
No. For those just tuning in, hopefully someone knowing flash better, the intro.html is now down, but when it was there, it was in the main directory along with the index.html
When you say the change brought a blank screen, do you mean the flash didn't work, or that you were no longer taken to the desired page after it stopped?