PowerPivot will not load

[SonjaPolitsch]

I am a college student working with Excel. I recently download the PowerPivot add-in for one of my assignments. When I click on PowerPivot tab then click on "Manage" I get an error message that states "We could not load PowerPivot add-in". I have connected with Microsoft and we ran the repair function, but this did not fix the error. Has anyone seen this error before? If so, how can I fix this? 

[#2]

Are you using an older version of Excel? The newer versions of Excel include PowerPivot from the start (All you have to do is enable it). I think it's much more stable in these versions.