Dreamworks must have thrown quite a bash when megastars Brad Pitt and Julia Roberts agreed to star in "The Mexican." If getting them to sign on the dotted line wasn't enough, both even took a pay cut so that the movie could maintain a reasonable budget. Studio executives must have been salivating about potential international box office revenue.

You would assume that the script, by J.H. Wyman, is of the highest quality. Not only did it garner the interest of two of the biggest movie stars in the world, but they wanted to be in it so badly they passed on millions of dollars and other scripts. Alas, Wyman's screenplay is convoluted and confused. It's hard to imagine what the two stars saw in it.

Pitt plays Jerry Welbach, a lovable but dim-witted loser who just can't do the right thing. He's a perpetual screw-up. Roberts is Samantha Barzel, his long-suffering girlfriend. She wants Jerry to move to Vegas with her and get married. She's sick of the way things are going for them.

Before Jerry can do anything, he has to complete one last job for the mob. They want him to go to a small town in Mexico and retrieve a valuable pistol called The Mexican. Sam isn't too pleased when Jerry tells her this. She throws a temper tantrum, kicks Jerry to the curb and heads to Vegas without him.

"The Mexican" cuts back and forth between Jerry in Mexico and Sam on her way to Vegas. Jerry is having a difficult time finding and keeping the pistol, which a lot of people seem to want. His misadventures, some of which are mildly amusing, are the best part of the movie.

Sam is having her own trouble. A hit man named Leroy (James Gandolfini) kidnaps her and might have to kill her, depending on whether or not Jerry is successful in his task.

The entire Sam and Leroy story is horrible and Roberts gives what may be her worst performance ever. Sam does nothing but complain and whine and Roberts is obnoxious and annoying. You have to wonder why Jerry even bothers to put up with her. He should be the one kicking her to the curb.

Pitt, on the other hand, emerges unscathed. His performance is light and charming and he is as likeable as ever. If "The Mexican" had focused entirely on his story, it could have been a good movie. But it's weighed down too much by the painfully weak and tedious Vegas storyline. And it's not sure what type of movie it is. Is it romance? Action? Comedy? All of the above? All involved really bit off more that they can chew.

Director Gore Verbinski ("Mouse Hunt") doesn't know when to say when. The movie clocks in at over two hours but it feels like five times that. It just refuses to end. Every time it seems like it's going to, it doesn't. The last 20 minutes or so constitutes cruel and unusual punishment.

There is a lesson here for Hollywood. Just because two huge movie stars are in a film doesn't mean it's going to be any good. Leave "The Mexican" in its holster.

Grade: C

"The Mexican" is now playing everywhere.