Unable to download/view file on website

I'm having an issue when trying to browse to, then download a file from a website with Internet Explorer 9 on Server 2008 Enterprise. When I try to download a file, it appears that Internet Explorer 9 doesn't recognize the file type. I get the option to open, save or save as when I click on the file. If I choose to open it, the file opens in another Internet explorer window. If we try to save or save as, the download doesn't complete. It appears that IE is renaming the document. If we click on the file and choose to save or save as, the file name appears to change from document.csv to document_csv.