Please help. A serious error has occurred while loading Sunset Valley. New Game.

Even if you haven't played on this computer yet, you could still have some issue in your new TS3 folder in Documents.  Since you have no content yet, why not just trash the folder and try again with a new one?  And just checking, but are you trying to launch the game while any of its folders are open?  If so, restart your computer and make sure all windows are closed before attempting to load the game.

You could also try disabling your antivirus software's realtime scanning.  Some programs have been known to interfere with the launching of TS3.

It would be useful to know the specs of your computer as well, so that you can get more specific advice.

@kittymew1234 If your computer is a pc, please post your computer's dxdiag - link - how to post your computer's dxdiag  Then attach the file created to the paper clip in the lower right of the response window.   thank you

I tried attaching the file you said to attached, not sure if it did.

You could delete the Sims 3 folder in Documents by manually dragging it to the recycle bin; the game would be forced to spawn a new one the next time you tried to launch.  There are plenty of causes of corruption in this folder, although it would be surprising if it was causing you problems before you ever had a chance to play.  Still, one potential issue is that your currentgame folder could be corrupted.  If you click on it and it won't open, that means the game can't open it either, which could cause the "serious error" message.  (Side note: that folder should always be empty when you're not actually in-game, so if you ever do find files in there, you should delete them.)

Trashing your TS3 folder should get rid of a corrupt currentgame folder, but if that's not the problem, there's only one other potential solution I can find:

http://simswiki.info/wiki.php?title=Game_Help:A_Serious_Error_Has_Occurred

I think you tried unticking the "read only" box, but there's another fix to try at the bottom of the page, under "still not working?"

@kittymew1234  A guess is the video chip (GTX 1050) may not (probably not) be in the game database and the game is crashing because of this. This is what I used to add my graphics chip to the database - link - Adding a new graphics chip to the Sims 3 database  It is not as hard as it looks but if you never did anything like this before a little help would be nice. I recommend copying the two .sgr files to a safe location THEN editing the files so you can recover if you need to.

Thank you to both of you, I'm going to try the deleting the Sims 3 folder thing first and if that doesn't work I'll try with the other one. :D

Ok so I looked into the adding the graphics chip one, but...it said to go into the Game folder and I checked to do that, my Game folder doesn't even exist! How is this possible? I bought the game, it's my Origin Library...

@kittymew1234  The two files you need to edit are in in the Origin folder. The user files in the documents fold will not be created until you scucessfully start the game the first time. The two files you need to edit are the .sgr files in the Origin game files.