LiLo and Sam: Trouble in Girl-on-Girl Paradise!

Exhaustion? B!tch, please.

As usual, the catch-all explanation for celebrities' mysterious trips to the hospital has been debunked - this time in the case of Samantha Ronson.

Apparently, Sam and Lindsay Lohan were involved in a "nuclear screaming match" at their Hollywood Hills home before Ronson was hospitalized.

Neighbors say they the best friends-turned-lovers were going at it at a fever pitch for quite a long time, but the feud reached a crescendo at around 4:00 a.m. after one of them screamed, "You never say you love me."

The screaming continued and neighbors heard a glass break.

It was at that point in which Sam was heard screaming at the actress, "If you're gonna break things, get out of my house." Sounds like a fair request.

One neighbor described the conversation as "wailing, with lots of obscenities."

A short time later Sam went to the hospital - her rep says for exhaustion.

Samantha Ronson joined Lindsay for a shopping trip on Tuesday and nothing seemed amiss. But is there trouble in this girl-on-girl paradise? Stay tuned ...