I'd say of all my aspie traits, having trouble dealing with breaking of routine or change of plans is the most prominent. I don't have a meltdown or shutdown, but can get very upset and confused, and have trouble processing what my next step will be.
For instance, I received a text message yesterday from a co-worker who was asking if I could work for her. I immediately felt defensive, and kind of, well, angry. Obviously, I could just say no, but my plans for the day weren't huge (finishing up a photo book for my niece, which I needed to have finished for today). None-the-less, I had some kind of plans, and couldn't bring myself to help her. However, I felt terrible, like I was being selfish/lazy. This happens a lot...if someone asks me at least a day ahead of time, I will usually be fine with going in to work, but if it is the same day, even if my plans are just to sit around watching TV, I can't bring myself to help my co-worker.
As I learn more about asperger's, I'm finding that I am more at ease and accepting of some of my quirks. I've always gotten so mad at myself for my sometimes 'lazy/selfish' behavior, but now I'm understanding the root of said behavior. That said, my boyfriend said yesterday that I looked absolutely pained as I was trying to decide what to write back to my co-worker; distraught, almost.