Help on setInterval function

I have problem with the setInterval function. I have a game application that sets a time limit of 3 minutes. From 3 minutes counting down by 1 second up to zero. The problem is, the counting of the timer is by 2 seconds and sometimes by 4 seconds. I tested the movie in my local computer and looks fine but when I upload it to a server and it is embeded in a website. And by the time the user clicks the link to play the game application and starts playing the problem about the timer occurs.:m2:

I’m in my third week of debugging and try to search in the internet of a possible answer or topic that is related to this problem.:hair:

Hope anybody could help me on this problem.

Thanks in advance.