Wall Street companies use high-speed trading software to generate billions of dollars in profits. Fans of performers devise their own programs to help their favorite stars win online popularity contests.

So some Baruch College students tried using a similar method to gain an edge in signing up online for a new semester’s classes. But instead of getting seats in the most popular courses, they got themselves in a bit of trouble. And so did the next few students who tried it. And the next.

In all, 19 Baruch students were told by the dean of students’ office to stop what they were doing, immediately. The customized computer script they were using to automatically log into the college’s course-registration system and check — and check and check and check — for openings in sought-after courses was creating so much digital traffic that it threatened to crash the computer system for the entire City University of New York, of which Baruch College is part, said Arthur Downing, the school’s chief information officer.

By the time technicians first notified Mr. Downing that there might be a problem, two student accounts had already queried the online registration system almost a million times. He said he wrote back, tongue in cheek, “Gee, they make me so proud.”