MS-Orifice
MS-Orifice has been increasingly problematic over at least the past decade. When we used MSO-2003, a customer used to send in docs also created in MSO-2003. However, our install would not read many of the submitted documents. To solve the issue, I would often load them into OpenOffice, save as MS-Office, and then our MS-Office would read them. As for the latest MS-Office... the interface is a total fustercluck! I've used a lot of application suites, and none have had such terribly-designed user interfaces. Radical changes often take adjustment, but good ones do make the advantages clear, after a while. A year with MS-Office 2010 have made clear to me that ergonomics were nowhere near the designer's minds when this turd was polished.