You can enable this back in Smart View , go to Add Ins , Disabled Items , Enable !!
Try getting it repaired(control panel->uninstall program rather than clicking uninstall click on the application name and in popup click repair) once rather than re-installing and reboot your machine once repaired.
if doesn't help try disabling that add-in and enable it through File->Options->Addins..!!
will try and let u know...
This generally happens if your excel gets crashed due to some reason / your system gets force shutdown. As suggested above, you can enable it.
Note: When you get that message to disable, do not click yes.