Game won't save

My game will not save. It says error code 21 whenever I try. I use mods and CC, but have taken them out, cleared my cache, and started a new CC and mod free save. It won't let me go past CAS. I can create the sim no problem, but it then freezes when I start to play. I have repaired the game and no dice. This has been going on since the most recent update. First day, it was a loading screen of death, and now the last two I have been having this issue.