This thankfully does not prevent you from not being able to play the game. It some times happens though if something happens to corrupt the game.
I've ran into this before a long time ago, but was luckily enough to have just saved and exported the family and house I was playing with, created a new game in the same town they were in or I went back to a previous save and all was good.
By any chance have you tried just loading a new game just for testing purposes? If the test game works and you can play Sims just fine it may be that you have a corrupted game-save. If this is the case, there may not be much that can be done if it's fully corrupted unfortunately.
There's not much on this error. However from what I have seen crashing troubleshooting tips seem to help some.
Here are some troubleshooting tips I have to suggest:
1. Go back to a previous save game. Or if you have a .backup file, rename it. If your current saved game has a backup - SG01.sims3; SG01.sims3.backup -- Rename your current game if you'd like or move it to the desktop. Then rename your .backup file to SG01.sims3 to see if that works.
:Note: To lessen this error from happening use the Save As option often and give it a name of SG01, SG02, SG03 etc. Then quit the game. This also allows you to have automatic backups in case you need them.
2. Deactivate Origin in Game -- Open Origin, Select Origin > Application Settings > Origin In Game and deselect to disable Origin In Game.
3. Delete Game Cache
http://www.carls-sims-4-guide.com/forum/index.php/topic,20732.msg401809.html#msg4018094. Run Ccleaner and it's registry cleaner
https://www.piriform.com/ccleaner/download (Standard Edition is Free)
-- This helps clean up temporary files, internet cache files and other files that are left behind that are no longer being used.
How to use CCleaner to fix PC issues
http://help.ea.com/en/article/how-to-use-ccleaner-to-fix-pc-issues/5. Try a Factory Reset -- Sims 3 Factory Reset - HowTo
http://www.carls-sims-4-guide.com/forum/index.php/topic,20732.0.html6. Depending on how long it's been since you last played you may want to check the mods and custom content. As there has was an Origin update to integrate Sims 3 into Origin which broke some mods. - Move the mods folder to your desktop and try to play the game to see if that helps it load.
----------
Reference Links:
Serious Error Has Occurred
http://sims3.crinrict.com/en/2012/11/a-serious-error-has-occurred.htmlGame Crashes (CTD)
http://sims3.crinrict.com/en/2011/01/error-game-crashes-ctd.htmlGame Help:Restoring Backup Saves
http://www.modthesims.info/wiki.php?title=Game_Help:Restoring_Backup_Saves