"[Diddy] just started screaming at her when he saw her," says the spy. "No one could believe it. He was screaming obscenities at her, and also screaming at Terrence Howard, who was with her."

Campbell, however, brushed it off. "Naomi played it totally cool," says the party guest.

Another source tells me that while the two used to enjoy a flirtatious friendship, their relationship soured under the influence of Diddy's baby-mama.

"Kim Porter hates her," says the snitch. "There was also an issue that Diddy had wanted her to be the face of Sean John's women's line - but didn't want to pay her."

But a third insider adds: "[Naomi's] circle of friends have been trying to help her get her life straight. But they feel all they've done has been in vain and she's constantly causing trouble. She's been a disloyal friend."