Loading a saved game - game is stuck with multiple pop-ups

When loading a previously saved game, I get stuck as soon as the game has loaded, as there is more than one pop-up being displayed and it won't let me close any of them. It also will not let me do anything else and the game is completely unresponsive. Other saved games, where there are no pop-ups (e.g. building on fire or you need more workers) will continue ok after being loaded.