There are many hypotheses about what happened on September 11th, 2001. One theory suggests that a cyber-attack originating from Osama bin Laden's Al-Qaeda terrorist organization was responsible for the attacks. Other theories abound about who did this and why. But no one can definitively know for sure who or what caused the dot.com crash on September 11th, 2001. The Internet was just starting to become a major part of our lives. It was one of the most revolutionary new technologies that had ever existed. On September 11th, 2001, the dot.coms were starting to take off.