For those of you that are using this great product that is PowerPivot, you may have seen this error recently : “In-Proc Engine : Could not open embedded data.”

In my case, it was due to the fact that I was using the CTP version of PowerPivot with the RTM version of Excel 2010. You can just  check the version number : if you see the following :

then you have to uninstall it and reinstall the RTM of PowerPivot and then everything will work !