If you are like me, you tend to accidentally double-click on families in a Revit project file and then end up opening them in the Family Editor when that is not what you want to do. It seems that the faster that you work, the more likely you are to have this problem, which compounds the issue. You can stop this from happening easily starting with the 2014 version.
In the Options from the Application Menu, go to the User Interface section.
Pick the Customize… button next to Double-click Options.
In the Customize Double-click Settings dialog box, select one of the other options besides “Edit Family”. My preference is “Do Nothing”.