Quicktime just will not work in my browser

Every time something that is used by Quicktime is on my screen, all I see if a blank screen with a question mark in it like so:

http://farm1.static.flickr.com/186/433908958_40d8fbaf15_o.jpg

I've installed it, deleted it, re-installed it, tried different browsers and I just can't view anything in quicktime. I'm using Windows XP> Most recent version of Firefox, so I just don't get it.

Please help me figure out why this isn't working. It is installed and running properly on my computer, meaning, I can open up the little Quicktime icon and watch a movie on the Quicktime site. Just not any videos on my browser.

Thanks.

 

Anybody?