My Sim automatically aged up shortly after loading a saved game. His status apparently got stuck that way. From there on out, despite receiving the confirmation that he had aged up, various important actions were greyed out and impossible to complete because they could not be done "while a Sim is aging up". This includes build mode, travel, manage neighborhood, and save game. I waited for about a sim day, and made all of my Sims sleep and wake up, but the error remained, despite all Sims having completed their aging up and not being at the end of that life stage. When exiting without saving to the main menu, all other older save games were also corrupted with this bug, and nothing could be accomplished in them while a "Sim is aging up", even though no one was actually aging up. Even when exiting out of that game to the main menu, certain actions like gallery could not be taken because a "Sim is aging up". In other words, the bug affected the entire game, not just that one save. Luckily, exiting completely out of the game and starting again fixed it, but I was really panicking before I tried that.
This seems at least partially related to the fact that certain important actions are impossible during life events that can bug-out or fail. I reported another similar bug where my game broke because it was impossible for my female Sim to have a baby because she couldn't reach the bassinet that was automatically generated in between the bed and the dresser in a small bedroom. Build mode and other things were not allowed to be accessed, although doing so could have easily fixed this situation. Instead, I had to load a previously saved game.
Windows 7, no mods or cc, disk version of game.