Re: A serious error has occurred while loading (name).world.

@sonic1236788  One cause of the "serious error" message is having the Sims 3 folder open while you try to load a save, so please make sure you close it before launching the game.  Just to be clear, have you moved the entire Sims 3 folder out of Documents\Electronic Arts and let the game generate a new one, then launched it without adding any content to that folder?  It's important to test with zero content in a new folder, just to be thorough.

If doing the above doesn't or didn't help, please run a dxdiag and attach it to a post.

https://help.ea.com/en-us/help/pc/how-to-gather-dxdiag-information/