The Mojave chapter of the Brotherhood of Steel has retrieved and cataloged a great many artifacts back when they were still running exploratory patrols on the surface, before Operation Sunburst forced them into seclusion. Over the past few years, the Scribes have used the sudden free time to work through the backlog, including holodisks retrieved from the wastes. It all went well until late in 2281.
In a rare lapse of computer security, Scribe Ibsen activated an unknown holodisk in the terminals, infecting the datastore with a nasty virus created by some hacker before the Great War. The virus was isolated to the historical data section, but keeps scrambling the terminals and jumping between them, making access impossible.
Talking to Scribe Ibsen reveals the conundrum he is facing. He will welcome assistance when the player offers their aid, believing that a fresh approach can do wonders.
To remove the virus, the player has to find three infected terminals in the span of 60 seconds. Their location is randomized with each try and Ibsen will give a signal when the virus jumps, so that the player can start the hunt. Scribes will temporarily move out of the data store to allow the player to do his job.
Infected terminals display taunts from the hacker, while uninfected terminals will only display gibberish. To purge it, all three infected terminals must be partitioned.
When discussing the virus with Ibsen, the player can suggest with Science 70 that giving read-only access to the kernel administrator can isolate the virus on partitioned terminals. The virus cannot jump to another terminal that way, so should the player fail in an attempt, the terminals will remain partitioned and there'll be fewer terminals to hunt down.
Alternatively, quicksaving at the start of the attempt allows the player to exploit the save and keep trying, as the script does not reshuffle terminals between attempts.
Once all three terminals are found, the virus is purged and Ibsen will grant the player access to non-classified topics in the data store.
Behind the scenes
The virus appears to be based on Creeper, the first computer worm created in 1971. Designed to copy itself via ARPANET to other machines on the network, the Creeper was not malware, but an exercise in programming. It did not scramble data, merely outputting a teletype message stating I'm the creeper, catch me if you can! before moving to the next machine.
PCPlayStation 3Xbox 360 Prior to version 184.108.40.2064 (update 3), the scripts governing the quest could break if the player used the Science 70 option and partitioned the virus multiple times. Reloading was the only possible fix, short of a mod. Alternative solutions included a mod/bugfix, later integrated into the Community Bugfix Compilation Patch.
PC Players could also fix in on their own by editing the HVHuntingVirusScript. Changing the line "if VirusTimer > 0 && NumberFixed==3" (without the quotes) to "if VirusTimer > 0 && NumberFixed >= 3" and then loading it as a plugin allowed the player to force the quest to complete.