: Sorry, Metalshark, I couldn't provide a link. Thanks for trying to help though. A colleague found this question when he was searching for a solution as well. The solution in our case was

Sorry, Metalshark, I couldn't provide a link. Thanks for trying to help though. A colleague found this question when he was searching for a solution as well. The solution in our case was fairly specific to a product we are using, but I will give the gist of it in case it helps anyone else looking in the future.

The problem came down to MIME types and how we were sending them across to other applications. Specifically we had to account for the following (some we already had, others we had to add to complete the set):

// Microsoft Office MIME Types for Excel and Word
PDF = "application/pdf";
XLS = "application/vnd.ms-excel";
LXLS = "application/excel"; // Legacy Excel MIME Type
DOC = "application/msword";
XLSX = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
DOCX = "application/vnd.openxmlformats-officedocument.wordprocessingml.document";

// Graphic file MIME Types
GIF = "image/gif";
PNG = "image/png";
PNGX = "image/x-png"; // Because M$ felt a need to be non-standard in IE7
JPG = "image/jpeg";
PJPG = "image/pjpeg"; // Because M$ felt a need to be non-standard with progressive JPEGs

Most notably the New Office types and the proprietary Microsoft image types were the fix.