X17 EXCLUSIVE - Lindsay Lohan Parties Until 2:30 AM, Leaves Club With Samantha Ronson

We knew she wouldn't stay locked up inside her Venice Beach home forever!

Lindsay FINALLY went out to get her party on last night, following her ex-girlfriend Samantha Ronson to their old stomping grounds - Teddy's nightclub at the Roosevelt Hotel in Hollywood.

Linds arrived in her rented Porsche at 1:45 am to the parking lot of the hotel, looking for Sam. Our photographer tells us:

"It was like old Lindsay -- she was desperate to find Sam. She jumped out of her car and ran into the hotel all nervous and wired."

Then, whadaya know -- Lindsay emerges with Sam and the couple get into Sam's BMW to head home to their matching two-story homes by the beach. Why'd they ride together and leave Lindsay's luxury rental in the VIP spot at the Roosevelt? A source who was inside the hotel last night (this morning) tells us:

"Lindsay didn't seem straight. She didn't need to be behind the wheel and Sam always takes car of Lindsay no matter what. Even though they aren't officially dating right now, Sam feels a responsibility for Lindsay so she told Lindsay she'd drive her home. Sam definitely feels like Lindsay is clinging and kind of stalking, but Sam loves her regardless and will always be there for her."

After jail time, a stint in rehab and now another threat of time behind bars, why isn't Lindsay ready to settle down and quit her wild ways?