Here are some hints on troubleshooting QuickTime problems.
1. You can check
your QuickTime installation at the Apple QuickTime Installation Check site at
http://www.apple.com/quicktime/download/
2. The Apple web site has a Live Streaming Check to check for problems (e.g.
firewall problems), see
http://www.apple.com/quicktime/troubleshooting/streamingcheck.html
3. Perhaps you are having trouble just with our videos? You can try
viewing other videos, for example, try viewing one of the movie trailers from
the Apple web site at
http://www.apple.com/trailers/
4. Still having trouble? You can see the QuickTime Support page at
http://www.info.apple.com/usen/quicktime/ .