Internet Explorer vs Mozilla FireFox

I put a mp3 player on my site.
The problem is when my member is using IE as their browser, the mp3 songs doesn't play they keep getting error message and I also disabled the right click but they still have access to right-click, and also when someone put a new post the icon doesn't change its still the same as no new post.

But when FF is used as their browser, the mp3 player is working fine, right click is disabled. The icon that there is a new post doesn't change also its the same as there are no new post with new post.

hello,

I put a mp3 player on my site.

my i remind you that puting copyrighted music in your forum is illegal and can induce the final delating of your board...

ok. lets leave the mp3 player problem alone.

how about the other problem, is there a solution to that!