If you are using the browser Internet Explorer 9, there are some cases in which a problem with the browser can cause this situation. The fix is to disable hardware acceleration.
For the quick fix, Click Here to Download the Microsoft Fix It File. Install the file once it finishes downloading.
For more information and Microsoft's documentation on the problem, please go here: http://support.microsoft.com/kb/2528233
Due to a recent Microsoft update, there is new documented issue with Internet Explorer and video streaming.
The issue is reported at the following link and related to not being able to see video in Internet Explorer: http://forums.adobe.com/message/5158696#5158696
Fortunately, there is a fix. Here are the instructions:
First uninstall Windows Update kb2670838:
1. Go to the Start menu.
2. Go to Control Panel.
3. Then Programs and Features.
4. Click View Installed Updates.
5. Find Windows Update kb2670838 and UNINSTALL.
Next Clear your Cache:
1. Go to your Tools.
2. Then Bowser Safety.
3. Then Clear Browser History and delete.
Make sure that "Use software rendering instead of GPU rendering" is checked:
1. Click on Tools.
2. Then Internet Options.
3. Click Advanced.
4. Make sure that “Use software rendering instead of GPU rendering” is checked under Accelerated graphics.