We have had reports of the Microsoft Excel 2013 PowerPivot or PowerView add-ins not loading in the ribbon.
When users then try to add the add-ins (File > Options > Add-ins) by browsing to the .dll’s in the COM dialog, they are not added as expected.
This problem can occur when using tools for migration, such as AppSense, and all personalization settings are not captured.
RESOLUTION: Follow the steps in the article below to allow Excel to rebuild the registry keys that are necessary for these add-ins.
2805999 COM add-ins are not displayed in the COM Add-Ins dialog box in Excel 2013 http://support.microsoft.com/kb/2805999/EN-US