The man credited with bringing down HP's CEO Carly Fiorina, who then blew the whistle on the company's spying techniques, now says he regrets leaving the company.

Tom Perkins denies he engineered Fiorina's firing, but says that he was involved in a “test of wills” with Chairman of the Board, Pattie Dunn.  At a crucial meeting, Perkins became so angry at her that he resigned from the Board of Directors. After he resigned, by his own admission, he waged a behind-the-scenes campaign to get Dunn removed as Chairman of the Board. Dunn called it "a vindictive vendetta" to tarnish her reputation. 

Perkins told CBS's 60 Minutes that he misses being on the HP Board and realizes he probably made a mistake resigning the way he did, and that he regrets it now.