Re: A serious error has occurred. It is recommended that you restart the application
@puppypower4 I'm not sure what you've tried, so I'll list the basics too, to be thorough. You can skip the unlocker though: it's quite old and might not even work anymore. It's also unnecessary, as there are much easier ways to change permissions in Windows 10.
Go into Documents\Electronic Arts\The Sims 3\FeaturedItems, and delete everything in there. Within the Sims 3 folder, go into DCBackup and delete everything except for ccmerged.package, which is necessary to make your premium store content work. Then delete the five cache files within the Sims 3 folder. In fact, while you're troubleshooting, delete them every time you quit the game. For reference, they are:
- CASPartCache.package
- compositorCache.package
- scriptCache.package
- simCompositorCache.package
- socialCache.package
Restart your computer, don't open any other apps (besides Origin if you use it to play), and launch the game. Don't open the Sims 3 folder either. Let me know whether you get the error again, and if so, when.
If you do still get the error, move your entire Sims 3 game folder out of Documents\Electronic Arts. When you launch the game, a clean folder will be created with no content. (Your save will be intact but temporarily inaccessible by the game.) Try to start a new save in Sunset Valley, just to see whether it works. Let me know either way, and if you still get an error, please run a dxdiag and attach it to a post.
https://help.ea.com/en-us/help/pc/how-to-gather-dxdiag-information/
P.S. Please edit out the mention of the NRaas mod that starts with a W. It can't be named on this site.