Ashley Greene and Nicole Richie spent time together as they attended an aerobics class on Saturday.  The two stars attempted to go incognito with giant sunglasses.

Nicole recently fired off an angry letter to the paparazzi who park outside her daughter Harlow's Los Angeles school, insisting they should be ashamed of putting young children at risk.

The socialite/actress posted the missive, aimed in particular at the snappers who work for top photo agency X17, on her blog - and she's threatening to play the vigilante in an effort to cull the paparazzo she feels are endangering the lives of kids and parents.

Meanwhile, recent reports speculated that Demi Lovato got into a fight with ex-boyfriend Joe Jonas' new girl, Ashley, prior to going to rehab. Greene's representatives have since denied this.

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