Hairy Situation, Part 2

Yesterday it was Mo'Nique and her hairy legs. Today it's a whole other hairy situation...and I totally need your help. Actually, my mom needs your help.

My mother went to get her hair cut the other day and was told by two stylists at the salon that her hair had a noticeable green cast to it. I can't see it, but I'm in no way a hair pro. Anyway, here's the deal. My mother has salt and pepper hair (that's more salt than pepper these days). She has never dyed her hair in her life (can you imagine that?). She doesn't swim. The water in her house is not overly chlorinated. She does take some medicines, but I am not entirely sure what she takes. She uses drug store brand hair products like Pantene and Head and Shoulders.

So here's what I need help with:

1. Have you ever heard anything like this before?
2. What do you think could be the cause of the green tint?
3. What do you think could be used to reverse this?

Any thoughts you might have would be greatly appreciated! My mother's not a fan of scene hair...she wasn't big on me having purple hair when I was a teenager and she's certainly not a fan of green hair on herself!