Well, either one file was corrupt and auto-repaired it via addon methods
Or your antivirus / Windows defender blocked the eso live folder last time and that was crashing the game due to missing write rights-> add the live folder to the whitelist of windows defender/your antivirus product.
Else it might just have been some other issue only related to ESO code, or not related to eso or the addons, maybe just windows (driver, firmware/other software ...)related.