We need a bit more information. How are you trying to convert this PDF file? Are you using Adobe Acrobat Standard or Pro and then try to save the file via File>Export To>MS Word..., or are you using Adobe's ExportPDF service (potentially via the interface built into the free Adobe Reader)? When you say you cannot convert the file, how exactly does the conversion step end? Are you getting an error message? If so, what exactly does it say?