Lindsay Lohan's Mom Drama

09/22/2006 at 07:50 AM EDT

These days Lindsay Lohan has toned down her partying and is "living clean," says a source close to the 20-year-old actress – but there's still plenty of drama in her life.

On September 14, a birthday dinner at New York City's Philippe restaurant for her mom, Dina, 44, turned ugly when, onlookers say, the older Lohan picked a fight with her famous daughter.

Lindsay "was miserable," says one witness, and stormed out, telling her mom to "go to hell."

After 17 years in showbiz together, tension between the two is only natural, says a source.

"(Lindsay) is no longer a teenager. She needs her mother less in a managing capacity and more as a family member."

Case in point: Just one day after their big birthday blowout, when the Prairie Home Companion star slipped on a wet floor at a Manhattan party and fractured two bones in her arm, her Long Island-based mother rushed to her side.