'Lindsay Does Drugs Because She’s Bored,' Source Says

April 7: Lindsay Lohan heads to an after party at the Roosevelt Hotel. (X17online.com)

Troubled starlet Lindsay Lohan’s problems weren't solved by two weeks in jail, or slightly longer than that in rehab.

By her own admission, she failed a court-ordered drug test last week.

"This was certainly a setback for me but I am taking responsibility for my actions and I'm prepared to face the consequences," she tweeted on September 17.

But according to one friend, Lindsay is still in denial, and can’t control herself.

"Lindsay does drugs because she's bored,” a pal of the actress told FOX411.com exclusively. “The only reason she’s 'fessing up about her drug use on Twitter now is because she knows that she has 'friends' that will sell her out. People have seen her doing the drugs."

And even though Lohan, 24, made the decision to use drugs after her release from rehab, she still blames others.

"Right now Lindsay is feeling really low -- really terrible,” the pal added. “She's like, "Wow, I got set up again.'"

According to the insider, the actress originally had good intentions. "When she first got out of rehab, she took it seriously. She didn't want to do drugs or get back into that lifestyle," the pal said. "But then, she had all these people around her who were doing drugs in front of her, and that's when she slipped.

"A few weeks ago, I saw Lindsay out, and she was in a weird state of mind. It was terrible. She wasn't her fresh self like when she first got out of rehab. It was like she didn't care anymore.”

But former bodyguard Lee Weaver still holds out hope for the wayward actress.

"Lindsay's a strong girl,” Weaver, who is currently writing a book about his experiences in Hollywood, told FOX411.com. “She will come back -- she just needs to surround herself with good people."

Lindsay's rep did not respond for comment.