Yep -- it's THAT photo again!

Now the Los Angeles Department of Children and Family Services is launching an investigation into Will Smith and Jada Pinkett Smith's care of their kids after a photo of 13-year-old daughter Willow in bed with 20-year-old male friend Moises Arias went viral recently.

Jada told X17online earlier this month, when we caught up with her at LAX, that there is "nothing sexual" about the photo. But it seems L.A. social services believes otherwise, according to a new report by RadarOnline: "The investigation was formally opened last week and is being taken very seriously by the department. Will and Jada Pinkett Smith have been extremely cooperative with officials. Of course, they arent happy that their parenting skills are under scrutiny, but they understand," an insider told Radar.

The website's source says investigators will be interviewing Willow separately and that they'll also talk to Moises -- it's claimed the inquiry will be a month-long process, not just a one-time thing.