Issue:
Suppose you have an Excel XML file and you try to open it in inside an Internet Explorer 32 bit version(by drag drop), it opens just fine in Excel on a Microsoft Office 2010 machine. But if you try to open the same XML file inside a 64 bit version of Internet explorer, you will find the xml text being displayed inside the browser instead of the Excel file being launched.
Cause:
iexplore.exe attempts to enumerate both Content Type- Text/XML and Content Type-application/vnd-ms-excel, however, in the failing x64 bit iexplore.exe it only enumerates Content Type-Text/XML but Content Type-application/vnd-ms-excel is NOT found in registry.
Resolution :
Adding the following registry entry resolves the issue and the Excel xml file opens fine even in the 64 bit Internet Explorer–
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\14.0\Common\Filter\text/xml]
"Excel.Sheet"="application/vnd.ms-excel"