Paris Hilton in Pledge This!

Paris Hilton's personal problems are mounting.

The hotel heiress is facing a massive pay-out to the investors of her 2006 film flop Pledge This! after a judge ruled she failed to properly promote the movie.

Bosses at Worldwide Entertainment Group sued Hilton and her company, Paris Hilton Entertainment, for breach of contract in 2008, claiming the socialite/actress failed to fulfil her promotional duties as the star of the movie - and demanded she pay back $1 million.

In a Miami, Florida court on Thursday, U.S. District Judge Federico Moreno ruled Hilton didn't live up to her contract by refusing interviews with publications in Russia and the United Kingdom.

He declared Hilton could be liable for a payout after valuing the lost promotional opportunities at around $160,000, according to the Associated Press.

It's the latest legal hassle for Hilton, who is facing up to four years in prison after she was charged with possession of a controlled substance following her arrest in Las Vegas on Friday night.