A nasty war between Doug Reinhardt and his landlord has resulted in a lawsuit in which the people behind The Hills are being sued for trashing some guy's house.

Man, no one likes that show anymore!

It began when Reinhardt, a.k.a. the boy toy of Paris Hilton, sued his landlord back in September, claiming the guy stiffed him out of a $21,000 security deposit.

Doug put that down on a Hollywood Hills home featured on the show. The landlord withheld it because Doug, he said, used it for The Hills without permission.

Moreover, the landlord also claims Doug Reinhardt and MTV caused "substantial physical and other damage" to the home while taping and is suing them for it.

DOUGIE LIKES: Reinhardt isn't smiling over this legal drama.

The landlord is going after Doug, MTV and Viacom for damaging the home and invading his privacy, plus he's accusing MTV of trespassing. Clearly he is not pleased!

He's asking for unspecified damages and attorney's fees.

Doug's rep shot back that he has photographic evidence proving he didn't trash the house ... and there was "no prohibitions to filming" in his contract with the guy.

He and Paris Hilton have plenty of experience getting the cops called on them for disputes at their respective places, but he's breaking new ground with this one.