On a point of fact:-
This is not the Default Key - it's the manufacturer's (i.e. Toshiba's) OEM_SLP Key
The problem is that the OP appears to have reinstalled Windows using a Retail disk, rather than the manufacturer's Recovery media, so the install is missing the proper licenses for the OEM_SLP Key to be able to self-activate.
Solution is the same, though - change the Key to the one on the COA sticker.