Had something similar to this after putting a new facepack in. My saved game still showed in the FM11 folder, but within the game the 'load last game' was all of a sudden greyed out an even in the 'load game' on the main menu screen it wasn't there anymore. I had to go into the FM11 folder, pull the saved game out and drop it onto my desktop then uninstall the whole game. When I re-installed the game(with appropriate patch) I then dragged and dropped the saved game from the desktop back into the saved game folder and then it let me continue the game once again.