Vandor IV is the planet where Paul Manheim's experiments with time caused deadly temporal distortions.
Vandor IV is the planet where Dr. Paul Manheim set up his laboratory to study time in We'll Always Have Paris. An accident during his work killed his research team, injured Manheim and sent waves of time distortion across space, causing the Enterprise crew to repeat moments.
The Enterprise travelled to Vandor IV, where an away team found Manheim and his wife Jenice. Data entered the laboratory, where the distortion produced multiple versions of himself, and sealed the rift with antimatter, ending the effect.