Sometimes it happens that PowerPivot crashes and is not loaded again automatically when starting Excel. Here is how you get PowerPivot back on track.

1. Open the “File” section from the ribbon
2. Choose “Options”
3. Choose “Add-Ins”
4. At the bottom on the right hand side you’ll find a select box labelled “Manage”
   1. Choose “Disabled Items”
   2. Click “Go …”
   3. Choose the item referring to PowerPivot
   4. Click “Enable”
5. Restart Excel

That’s it. In my experience no handicaps are to be expected. The crashes seem pretty random to me. Like a sudden nervous breakdown – just that Excel doesn’t need time-off to recover.