About the Error
This error code may present itself if you are attempting to open a Microsoft office for Mac document. It can occur as a result of several situations. If you created the document with the Microsoft office for Mac Test Drive, and Office Test Drive is in the Trash, the error will occur. Also, if you have more than one copy of Microsoft Office for Mac on your computer, you may see the error. Further, if the Mac OS X Finder cannot locate the Office for Mac program associated with the document, you will see the error. Lastly, the error may result if the file has the wrong file extension.
Windows Macintosh fault 10660 - Read the solution
To address the problem, first, verify the file name extension. On Finder, click on Preferences, then the Advance tab. Select Show all file extensions, and then close the Preferences dialog. Click on the document you are trying to open, click Get Info, and click the Name & Extension tab.Clear Hide extension. Then, look for the document extension, and type in the appropriate file extension.
If the problem is with having multiple copies of Office for Mac, then remove additional copies from your computer.
TipFor more information, please see: How to fix Macintosh error #10660