This error occurs when you try to view pdf files inside another programs' window like Internet Explorer or a content management application.
In order to solve this, you can try to uninstall Adobe Reader software from your computer. If you cannot uninstall it by the normal way, you can try to use a third party tool like Revo Uninstaller.
You can try to download and install the latest version of software by visiting Software Informers application web page in order to obtain a download link or visit the following official website.
For more informations about this matter you can visit the following forum.