It's a setting somewhere...I've had this problem before.
Go to "Start -> Control Panel -> Quicktime" to open the Quicktime Settings window.
Go to the Browser tab and click the Mime Settings button.
Under each category, select the media types you wish Quicktime to handle in your browser. Do not enable Flash.
Suggested Mime Settings
Important: When selecting the media types you want Quicktime to handle under "Mime Settings", make sure that "FlashPix" (under "Images") and "Flash media" (under "Miscellaneous") are not enabled, as doing so will cause a conflict with the Flash Plug-in.
Next, go to the File Types tab (still in QuickTime) and select the same options as you did under browser MIME types.
Close and reopen the browser to effect the changes.