What did you do, reinstall all your stuff?
Well.. it was quite simple.
What I did was -
1. Move DCCache and Mods folders from The Sims 3 folder in My Documents to Desktop.
2. Find the spellbook .sims3pack from the Downloads section.
3. Double-click it. Let the launcher install it.
4. After it is installed, restart the launcher to check if the problem is repeating or not.
5. It didn't repeat. Do the same thing again to believe your eyes. Again, the spellbook is installed and there.
6. As a matter of fact, I didn't need to seek all the sources I got my CC from. All the CC I uninstalled temporarily by moving out DCCache is
still kept in the Downloads folder in The Sims 3 in My Documents.
7. Click "Select All" and then "Install". Wait for the launcher to reinstall everything.
8. Double check.
9. Send PJ a zillion cyber-hugs.