When you try downloading one of the Office 2007 file types such as .DOCX, .PPTX, .XLSX, the file may download as a .Zip (Compressed Folder). This happens if the Office 2007 file format MIME types are not registered in the Web server you’re downloading the file from.

There is nothing much the user can do, apart from saving / renaming the file with the correct extension and then opening it using Office 2007.

If you had already downloaded the file (as .zip), simply rename (change) the extension accordingly. To do that, you’ll have to clear the Hide extensions for known file types check box in Folder Options. (REF Show or hide file name extensions)

Note to Webmasters

If you’re a Webmaster and want to register Office 2007 Open XML File Formats in your server, visit these links for detailed information:

Office Resource Kit Blog : Register Office 2007 file format MIME types on servers (Windows / IIS)

Serving Office 2007 documents from a Linux PLESK web site (non-Windows)

When you attempt to enable or disable an Office Add-In, the following error message may be displayed and the Add-In state does not change. (more…)