She played the character of Susan Fields for all four seasons of the show.
There are a couple of common misconceptions about her departure, though:
* Some might be confusing her with another character: The show had a few female characters, and some viewers may be recalling a different actress who left after season one.
* She did leave the show after four seasons: This is true, but it wasn't during the first season.
Let me know if you have any other questions about the show!