Intrusion prevention systems are becoming increasingly essential to combat today's automated threats. However, people are wary of using these systems because blocking false positives will result in a loss of legitimate functionality. In this presentation, wediscuss the false positive issue in relation to intrusion prevention, and what the implications are for system design. In particular, we borrow some ideas from immunology to better understand how to design systems that are false positive tolerant and robust in today's complex environments. Dr. Steve Hofmeyr received a in Computer Science in 1999 from the University of New Mexico (UNM), focusing on immunological approaches to computer security. During his studies, he spent a year at the Artificial Intelligence Lab at MIT. After finishing his he was a post-doctoral researcher at UNM, and closely associated with the Santa Fe Institute for Complexity Studies. Dr. Hofmeyr has authored and co-authored many papers published in conference proceedings and peer-reviewed journals on computer security, immunology and adaptive computation. In 2003, MIT's Technology Review named Dr. Hofmeyr as one of the top 100 young innovators under 35.