@AddyAva Try downloading fresh copies of your mods and custom content. There are issues with copying over some files, mostly or entirely Sims3Packs and the bundled .dbc (cc) and .ebc (store stuff) files that result from installing them. But it's best in this kind of situation to download new versions of everything and add the content slowly, testing each time to make sure the game still runs.
Start by moving your entire Sims 3 folder out of Documents > Electronic Arts and onto your desktop. Open the launcher to create a clean folder, make sure the game runs, and then download some content and see how it goes.
