I currently have a new single server SP2010, this is not an upgrade but a clean install (chose farm so I could define SQL). The issue is that .xls, .xlsx, ,pdf (even though I have added the icon to the \images folder and modified the docicon.xml) all show up as red X's in libraries. This is not the issue that I keep finding online where the icon works just fine execpt in search results. This is in the actual library. The issue is happening on all sites from the root down, and with all users including the admin. What I find odd is that .doc and .docx work just fine.