This. Honestly, I would have stopped answering her calls by now. She sounds utterly obnoxious, and I'm at a loss as to what maintaining the relationship adds to your/DH's life.
Wait...what? Are you implying the OP and her DH should give his mother the cut direct because she's a bit annoying/obtuse about computers?

Okay, I was a bit flummoxed by what I was reading too -- couldn't believe anyone would suggest cutting their mother out of their life due to one annoying habit. We all annoy our loved ones from time to time. None of us is innoculated against irritating others. If we cut everyone who annoyed us out of our lives, well, we wouldn't have much of a life any more.
According to the OP, she doesn't like visits, doesn't like phone calls, and Mmms instead of cooperating when OP is trying to help w/ the computer. So yeah, I just don't get the point of these interactions.
Hookay, so this is going weird places...
DH has had a very turbulent childhood. He didn't get to see his mother between infancy and the age of 14. He never really knew his mother as a proper child, and as a result has always had something close to an adult-adult rel
ationship going on with her. It is not a mother-son rel
ationship at all, but largely as a result of circumstance (it was absolutely out of her hands at that point for reasons I will not go into). To be suddenly presented with a teenager and be told, "this is your son, suddenly be a mother" is pretty huge, and she (like most people would also) never had the chance to learn to be a mother as one normally does: the rel
ationship evolving as the child grows into something more and more complex. Both DH and I agree that it is worth expending effort to have something of a rel
ationship going, because although she hates socialising and it stresses her considerably, small things she has said and done over the years have indicated that she is somewhat happy knowing that her son doesn't just treat her as some complete stranger woman, as happened to one of her university peers with tragic results. She'll never be able to have a real parent-child rel
ationship, especially with her personality, and that's fine, but if we can give her this small comfort then it's worth it.
A number of times, she has done very inconvenient things (for her) just to make a small gain for DH, but always way behind the scenes since she hates having to deal with the person she's trying to help. She once said, "I couldn't give him the right things when he was a boy, so now I do whatever I can twice as much. If only he were younger, though, because I can't give him much when he's already so grown-up." DH's intense self-sufficiency is troubling for her, because on the one hand she doesn't have to spend time with him at all, but on the other she feels like she owes him what he missed out on as a child, and now he doesn't need it.
Further, I no longer have
any family to speak of (big and painful cut). And nothing MIL would realistically do would ever compare to what I used to take from my own parents, so cutting her out to me would be completely ridiculous and over the top. She is stubborn as an ox, frustrating, and antisocial, but she isn't nasty, mean, selfish, or aggressive. Just difficult. There's a difference.
And yes, I am writing this partially because, reading back, I feel guilty for painting MIL in a bad light when she isn't a bad person.