44. Episode 5851 (Wed 23rd Feb 2011)

Worried for her friend, Lisa tells Derek to stay away from Lizzie. Calm, Derek replies that she's overstepped the mark - they had a fling but she doesn't get to tell him who to talk to. Later that day, Lizzie gets sick of Lisa's moods and accuses her of petty jealousy when she makes a cutting remark.