Lynne went to visit a sick relative in Kansas and was never heard of again. It was right around the time Paul lost his office in Newman Towers and moved in with Michael and Christine. Made absolutely no sense character wise why Lynne would up and leave just as Paul was moving offices.
First sign of the impending budget cuts where sets disappeared and supporting players were axed.
It was at the same time that Jerry Birn a long time writer on the show was let go. He was Laura Lynn Birn's (Lynne) father. All very coincidental.