Hoping to slow a growing storm of criticism over a controversial leak probe, Hewlett-Packard said that Patricia Dunn would step down immediately as chairman and board member, to be replaced by CEO Mark Hurd. However, Hurd also confirmed on Friday that he knew about several key phases of the investigation and attended meetings at which the investigation was discussed. Hurd said he was e-mailed a report summarizing the investigation but that he did not read it.