Clothes get bleach like stains in the Washing Machine?

I have a Kenmore Heavy Duty model 110 that came with the home I moved into 2 years ago. One of my housemates (there are 3 of us) has problems mostly with her cotton shirts - they come out of the washer with stains that look like they've been very lightly bleached. We line dry and it's almost as if the sun has done this but it hasn't been an issue for any of the rest of us. She's tried different detergents. None of us use bleach in the washer. She says it's nothing outside of the home that she does (no use of bleach at work). It's happened to me a bit but not to the same extent as her. Can you figure it out? I'm at a loss.