You can save your Sims the same way you save your Saved Games - in same place you can find folder named Saved Sims with all the Sims you saved in CAS. Same goes with Export folder - all your exported files, Screenshots, Videos and Downloads.
I looked around for this problem, and it may have something to do with some hairstyles. I would also suggest to remove all CC from the game and try it to see if it repeats. I didn't see anyone report connection with Mods but it's worth to try without them too (just renaming Mod folder will do the trick).
Also, make shore your drivers are up to date. For some reason that was mentioned as a possible cause for this error.
I did full reinstall of the game just few days ago, and I do it around once per month -I do a lot of shuffling around with game, and for it to run smoothly I tend to do a clean install every time something goes wrong (like crashing, or failed saving etc.) It can save you a lot of time you might lose while trying to fix something that can be avoided by clean reinstall of the game. Revo uninstaller will speed up the process of registry cleaning etc so I would recommend to do a full reinstall as a part of maintainance of the game
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