Four people sitting in an office with their personal laptops. One is running Vista with Office 2007, one running XP with Office 2003, one running Office for Mac, and one (me) running XP with Open Office. Our Office for Mac user opens an Excel spreadsheet (originally created on a Windows machine) which contains several XIRR formulas, and for no good reason, the calculations are borked - everything is hard-coded. The XP Office 2003 user then opens her copy of the same spreadsheet, and gets the same result. Office 2007 man has a go, and also fails. As a final act of desperation, the Open Office user opens the Excel file - and that's right, the formulas work flawlessly. Saves file, sends back to other users, all of whom can now use the sheet as it was intended.
This has happened twice, and none of us can explain it.
If not for whatever magical healing fix Open Office seems to have applied, we would have come to the depressing and unavoidable conclusion that the sheet would have to be rebuilt - an unappetizing and time-consuming proposition. Rather than rant about Microsoft, let's just let the facts speak (very loudly) for themselves.