12/16/2008 at 02:00 PM EST
Tara Reid has long been known as a party girl. But the American Pie
actress, who entered rehab
last week, is trying to change her life for the better.
The specific reason behind her decision to check into Promises Treatment Center had not been revealed, but a source tells PEOPLE in its new issue: "Tara has a problem with alcohol. It’s been at the root of much discomfort between herself and her family and friends."
In fact, the source says that Reid's relationship with her family and close friends "has been strained" recently. "She becomes erratic and is a completely different person when she's intoxicated, which is hard for people close to her to watch."
Earlier this year, Reid, 33, told PEOPLE she’s a "social drinker," but denied using drugs. "I've done enough [partying] for a lifetime."
So now Reid, who is dating her Mantra clothing line design partner Julien Jarmoune , seems ready to make a real change in her lifestyle. "She finally made the decision to do something positive for herself and her loved ones," adds the source.
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