Thank you for posting the error message. That really helps when it comes to searching for tips and tricks to help fix the problems.
How old is your save game (sim weeks/days)?
It sounds like it's an older game. But if you're willing to do a test-game. Give this a try.
Save a copy of your Sim family. Create a new game. Then play that family for awhile to see if it lags and or can't save. If it still lags or can't save, then we need to dig deeper. But if it works better then it sounds like your game maybe getting to big. Best suggestion I've found is to save back a copy of the family in house and start a new game with them.
After awhile of playing Sims, in-game time and real time wise. Things can go wonky within the game and it's just best to give it a new start.
Something else you may try is going over your family's inventory and their personal inventories to get rid of some of their stuff. Stuffed inventories causes lag as well.
Something that I see that might help that isn't on your list is to delete the cache files - (socialCache.package, Sims3Logs.xml, simCompositorCache.package, scriptCache.package, compositorCache.package, CasPartCache.package)
-- Also delete everything except Ccmerged.package file in your DCBackup folder.
-- Documents > Electronic Arts > The Sims 3 > DCBackup
If you'd like to read up on some more tips here's a link to have a peek at.
Game Crashes (CTD) Example: Sims 3 Stopped Working
http://sims3.crinrict.com/en/2011/01/error-game-crashes-ctd.htmlI wanted to add a couple more links that might be helpful too.
How To: Save a Household
http://www.carls-sims-3-guide.com/forum/index.php/topic,19060.0.htmlSaving folders/files to use on a different computer or to use as backup
http://www.carls-sims-3-guide.com/forum/index.php/topic,16414.msg313134.html#msg313134MrsFlynn