Lindsay Lohan made an appearance on CBS' Late Show Tuesday night, in what was her first interview since she resolved her car crash case last month. However, she was reluctant to discuss her legal woes and her impending rehab stint with host David Letterman.

After Lohan walked out on stage, Letterman ran down all of the jokes he's made at her expense in recent months. He then asked pointedly, "Now, aren’t you supposed to be in rehab now?"

Lohan answered that she must check into rehab by May 2, and that she must spend three months in the facility and will be spent at the Seafield Center in Westhampton Beach, New York.

After Lohan noted that she's been to rehab several times in the past, Letterman wondered aloud, "How will this time be different?  What are they rehabbing, first of all?"

Lohan sidestepped the question, telling Letterman, "I’m the happiest when I’m working and the healthiest, and I think this is an opportunity for me to, you know, focus on what I love in life.  And I don’t think it’s a bad thing. I think it’s a blessing...and not a curse."

Letterman pressed Lohan on the specific type of treatment she will receive in rehab: "Is it, like, alcohol?  Do you drink too much?" Lohan shot back, "We’ve discussed this in the past." Letterman joked, "Did we really?  When did we discuss, now I’m the one who’s having the blackouts...I oughta be at rehab."

Lohan later remarked that in the past she's put herself in situations that made her vulnerable. She said she has acted immaturely but is looking forward to moving on with her life and continuing her career.

Lohan was on the show to promote her upcoming appearance on Charlie Sheen's FX comedy Anger Management as well as her role opposite Sheen in Scary Movie 5, opening Friday. According to sources, LiLo and Sheen will walk the red carpet together at the movie's premiere in Los Angeles this week. "Imagine your date for the evening being Charlie Sheen just a few days you are meant to report for rehab," quipped an unnamed source.