Microsoft may partner with investment firm Silver Lake Management to take Dell private through a leveraged buyout, possibly chipping in about $2 billion to the deal, a person with knowledge of the matter said on Jan. 22. For cash-rich Microsoft, propping up the seller of PCs and tablets that feature its software makes sense, as PC shipments face a prolonged slump and both companies struggle to mount a credible response to Apple and Google's mobile dominance. The Dell investment could ratchet up tension with Microsoft's other hardware partners, already displeased by the software company's foray into making tablet computers. Samsung Ventures Investment, the South Korean mobile handset maker's investment arm, bought a stake in a mobile security company to lure business and government clients away from Research In Motion's BlackBerry franchise.