Cause for "A script in this movie is causing Flash Player to run slowly" alert
Issue

While viewing a Macromedia Flash movie in any Macromedia Flash Player environment (browser, standalone, or projector), an alert appears stating "A script in this movie is causing Flash Player to run slowly". Additionally, the message box gives the viewer the option to abort the script, as can be seen in Example 1.

Beware of trying to do too much in flash: this alert will kill you.