That sounds to me like a little problem, not a game-ruining problem, that we ought to be able to figure out. Can't imagine there's something blocking her from getting out of bed, since she can obviously get into it, but have you tried placing the bed somewhere else to see if that makes a difference? It sounds, also, like it doesn't happen every time she's getting up? (Not sure what difference that makes, but it might give someone other than me an idea.)
Since you've already replaced the bed, maybe you could try resetting the lot by moving it (without your household) to your bin, bulldozing the one on the map, and then replacing it with the one you saved. While you do this, you can either evict your household and leave on the sideboard, replacing her/them once you've replaced the lot, or you could move household to a different lot and then back once you've replaced it. If that doesn't work, maybe just move household to a different lot/house altogether and see if the problem persists?
