Yes, I totally agree Gee that if you feel you are constantly chasing such errors this would be frustrating. Some people will be more careful to ensure the same mistakes don't happen again but others, well, perhaps they won't.
Don't take this the wrong way Gee but do you think that possibly when you bought this mistake to her attention, as you were feeling annoyed such a mistake happened, you may have sounded a little abrupt or irritated and she may have reacted in the way she did as she picked up on this tone in your voice? If this is not the case, then as I said before, you may have caught her at a difficult moment in her day.
Obviously I was not there so don't know how you spoke to her but the reason why I mention it is because I know that people in my office react as your lady did when things go wrong and they are 'pulled up' and I am sure the person who spoke to them did not necessarily mean it to but they came across in an off-hand/scolding manner.
Party invites for example, yes you have a good point here and nobody would deliberatly send anything out that was wrong I am certain, but mistakes do happen - part and parcel of office life. I think the thing is learning to accept this is part of office life and not to dwell on it and feel negative. Some things/people you have no control over. Frustrating yes, but stuff happens. Keep smiling
