Whenever you have a big activist investor — we used to call them vulture capitalists, corporate raiders and a lot worse — breathing down your neck, it makes running your company that much more complicated…and uncomfortable. Is that what new Lowe’s CEO Marvin Ellison is dealing with now that Bill Ackman — the man who led the destruction of Penney and has made a colossal number of bad investment bets — has a sizable holding in the home improvement retailer? That’s what I speculated on in this Forbes.com posting: