A navcomputer virus represented a type of computer virus that rendered a ship's navicomputer inoperable, thus preventing navigation in either real or hyperspace.
In the course of the Stark Hyperspace War, the Stark Collective engineered a navcomputer virus. They transmitted it to Ranulph Tarkin's paramilitary by embedding the signal within Nute Gunray's location-finder signal. This virus resulted in one-third of Tarkin's fleet jumping to locations where their ships would be destroyed (e.g., within planets or stars), another third appearing safely in realspace but dispersed across the galaxy, and only one-third successfully arriving at Troiken.
Subsequently, many years later, the navcomputer virus was modified for use in the Iron Eclipse project.