A planet suffering an outbreak of Correllium fever in 2366, for which the Enterprise was transporting specially prepared tissue samples supplied by the Mikulaks.
Nahmi IV is the Enterprise's destination in the Next Generation episode Hollow Pursuits. The Mikulaks have donated tissue samples that may help scientists contain an epidemic of Correllium fever on the planet, and the ship takes them aboard for delivery.
The medical containers turn out to be the source of a string of baffling malfunctions. One is leaking invidium, a substance no longer used by the Federation and invisible to ordinary scans, which is carried around the ship on the hands and uniforms of the crew.
The contamination finally jams the warp drive into a runaway acceleration. Reginald Barclay's reasoning helps Geordi La Forge's team identify the cause in time, and the ship diverts to a starbase for decontamination.