Well... this is from MozDev's website (mozilla projects and firefox development resources), but it might still work.
What to do if QuickTime takes over handling Flash content
When you install QuickTime, or change your QuickTime settings, it may take over handling of Flash files. However, this can be fixed quite easily. To stop QuickTime from handling Flash files, do the following:
- Close Mozilla (or Firefox)
- Open the QuickTime Control Panel
- Select "Browser Plug-in" from the dropdown menu
- Open up the MIME Settings dialog
- Make sure "Flash file" is not selected. This is listed under Miscellaneous.
- Click OK, and close the QuickTime Control Panel
- Remove the file pluginreg.dat from your Profile Folder. This file will be recreated next time you start Mozilla
- Remove npqt*.dll from your Mozilla or Firefox plugins folder. These files are not required, and can cause problems when QuickTime is upgraded
After doing this, you may need to reinstall Flash Player. These instructions should be the same for both Windows and MacOS X, with the exception of the last step.
Well, Step one, you would close IE, instead of firefox.
You do not need to perform steps 7 and 8.
That will hopefully fix it. :S