Based on new reports, Sculfor spent six months in intensive treatment for cocaine addiction in 2004. He's notorious for being a serial womanizer and cheater, and he's an aspiring actor who may be using Jennifer Aniston for fame.

A mutual friend of Brad and Jen tells Star, "Brad thinks this Sculfor guy is pretty shady. Brad relayed to Jen through friends that he is concerned about her. Paul might be handsome and charming, but Brad wishes Jen would look at the whole picture."

Sculfor's engagement to British model-turned-TV personality Lisa Snowdon ended when she broke it off, after he was reportedly cheating on her. Lisa later dated George Clooney for more than a year.

Sculfor's publicist, Julian Payne, tells Star, "Paul has never made any secret of his past. He's been on several dates with Jennifer, and I'm sure she knows everything about him. He's not trying to hide anything."

When asked about Sculfor's steamy photo shoot in the February 1997 issue of the now defunct British gay publication, Attitude, Payne responded, "That was a long time ago. I don't know if they were nude pictures." Sources who have seen the spread say it's "sexy as hell."

"What Jen doesn't know is that gays love Paul. He thinks that a great joke and doesn't object to the adulation," says an insider.

According to insiders, Jen first met Sculfor at a a party in L.A. last winter when she was still dating Vince Vaughn.

Says a source, "Paul must have been keeping tabs on Jen, because as soon as he heard she and Vince were broken up, he immediately got her phone number from David Arquette -- with the blessing of his wife, Courteney Cox, Jen's closest pal. David did have some reservations and warned Jen that Paul is a fameseeker and that she should be wary." Arquette's rep denies the story.

"A lot of Jen's friends -- Brad included -- think Paul is probably using Jen to get ahead, "says another source. In fact, Sculfor has mentioned that he planned on modeling for four years before becoming an actor.

On June 10, the next morning, Sculfor was seen leaving Jennifer's Malibu beach house at noon. This wasn't the first time they have spent the night together. Star has new details about the couple's romantic Memorial Day Weekend at Shutters Hotel On the Beach, a luxury hotel in Santa Monica. On May 26, the couple shared a two-hour meal of seafood, salad, and wine at the One Pico restaurant where they looked lovingly at each other. Onlookers observe, "Paul spent four nights at Shutters. He ordered room service for two a couple of times!"

Jen's friends are becoming more concerned that this romance may be headed for heartbreak. However, Jen's rep denies it.

"Jen got a phone call from a friend who had spoken to Brad. Touchingly, Brad wanted her to know that he's worried that this guy will hurt her if she doesn't watch out," says a source. "A lot of Jen's friends agree with Brad. They think Paul is after the spotlight and probably using her to get ahead."

Some of Sculfor's friends are even warning Jen about him. "Paul got Jen on the rebound. I hope she has the sense to back off. She's mixing with a guy who has a terrible track record with drugs and women," says British TV host Rick Sky, a one-time acquaintance of Sculfor.