@Aptmass Sorry for the delay; this is kind of a weird one for me. Just as a test, could you download a player-made save and try to load it? This will distinguish between an issue in creating a new save and one with loading some other process of the game.
Since you have all packs, you could try either of the saves provided in this post:
The player who made them was fixing Isla Paradiso so that it ran better; she provided her saves so that other players could benefit as well.
@Aptmass Have you ever successfully run Sims 3 on this computer before? Even if you haven't, it's theoretically possible that some file in your game folder is already corrupt. It's easy to fix: Drag your entire Sims 3 game folder out of Documents\Electronic Arts and onto your desktop, and try again to load a new save.
If that doesn't work, please run a dxdiag and attach the results to a post. The information in it will cover a lot of possibilities at once, so it'll be easier to know where to start troubleshooting.
Please also list the packs you have installed.
@Aptmass I need a dxdiag on this computer.
Or, if this is a Mac, let me know, and list your specs, as described in this post:
@Aptmass I just need the one file, the complete version with all the information included. All the instructions you need are in the link I posted.
@Aptmass Try removing your entire Sims 3 game folder from Documents\Electronic Arts. You can just put it on your desktop.
If that doesn't help, temporarily disable your antivirus/firewall, just long enough to test the game. If it works, you can set an exception for TS3W.exe, with the "W."
If that doesn't help either, temporarily disable OneDrive, again just long enough to see whether it makes a difference.
Finally, make sure .NET 3.5 is enabled; sometimes it's not by default. Here are instructions; scroll down to the "enable" part, since it's probably already installed.
If none of this makes a difference, let me know.
@Aptmass Try playing with your computer completely offline, as in, turn off wifi and/or unplug the ethernet cable.
If that doesn't help either, I'll ask someone else for advice, but it might take a little while to get a response.