From the 1.102 release notes:

http://media.xfire.com/xfire/readme.html

Long-time users running the Xfire skin will be switched to the Shadow skin, in the old-colors Xfire theme, during this update. You may switch back if you so choose.
The reason for this change is so that users running the default skin (Shadow) will always have the most up to date supported features of Xfire.

The classic Xfire skin will no longer be shipped with the Xfire installer and new features will not be developed for it.