You have Office 2004 or an older version. Only Office 2008 and 2011 are compatible with OS X Lion and Mountain Lion, because Apple dropped PowerPC applications support with OS X Lion.
In your case, you have to install a new application to open your saved files. You have three possibilities:
1. Purchase Office 2011 > http://www.microsoft.com/mac
2. Try iWork (Numbers, Pages and Keynote), available in the App Store.
3. Use LibreOffice (completely free) > http://www.libreoffice.org
All of them can use Office files, so first try LibreOffice
Office 2004 does not work under Lion or ML because Rosetta (the interface used to run PowerPC-compiled apps) is gone.
You can use Office 2008 or 2011.
Read this for other apps that do not work under Lion or ML: http://roaringapps.com/apps:table
Not to talk down LibreOffice or OpenOffice (both nice free alternates to MS) ...
Sometimes *small* things are imcompatible. Like the bullet point that is a circle in MS Office looking like a triangle in LibreOffice.
Or big things like not beaing able to open ".xlsx" files with even minimally complex formulas.
But if you can live with these issues, the price is right.
Peter Dino wrote:
I just upgraded to Lion 10.7 and when I clicked on Word, Powerpoint and Excel down in my Dock I got this message: "You can't open the application Microsoft Word because PowerPC applications are no longer supported." WOW.
I didn't know this.
I have all my very important document in these three applications which I absolutely need.
How do I get to them. What do I do?
If you are unable or unwilling to update to Office 2008 or 2011, you can install Snow Leopard Server (with Rosetta) into Parallels or VMWare Fusion and continue to use Office 2004 (and most other PowerPC applications) concurrently with Lion or Mt. Lion:
[click on image to enlarge]
Snow Leopard Server is now available from the Apple Store for $19.99 + sales tax & shipping: 1.800.MYAPPLE (1.800.692.7753). Apple Part Number: MC588Z/A