I have never had this problem, but it sounds as if you may be missing a codec, Firewall issue, or you may have to increase the amount of memory the player can use on your computer.
This is the best I could do guys, follow along and see if this solves your problem Quik Time Installation check, if not I would un-install it and then re-install it.
Most probably a codec issue. Download Nimo codec pack and you will rarely have any problems.
Alternatively, you can check if you need a codec by downloading g-spot codec information and running a test. After learning what codec you need, go to www.fourcc.org and download the codec in question.