Someday someone will make a great movie out of a John Irving novel. "Simon Birch" is not it.

Actually, when it tries to be faithful to its inspiration, Irving's novel "A Prayer for Owen Meany," this comedy-drama is OK, if somewhat unspectacular. Unfortunately, after the first hour, it deviates greatly from the source and things go seriously awry.

To be fair to filmmaker Mark Steven Johnson, maintaining the book's balance of humor and tragedy would be difficult. But he seems to be striving for tears only. And this film will get some somber reactions — many of them from faithful Irving readers.

Also, you hate to criticize young actors, but newcomer Ian Michael Smith's performance is so stiff and self-conscious that it proves too great a distraction for the movie to overcome.

As played by Smith, Simon is an unusually tiny youngster with a huge belief in the power of miracles. His best friends are Joe Wenteworth (Joseph Mazzello, from "Jurassic Park"), and Joe's sympathetic mother, Rebecca (Ashley Judd).

Both boys are devastated when, during a Little League baseball game, Simon accidentally kills Rebecca with an errant line drive. Suddenly united in purpose by the tragedy, the two become consumed with discovering the identity of Joe's biological father, and in proving to disbelieving town residents that Simon really is a miracle of sorts.

The film is likable enough, if a tad lightweight, through much of the first hour. That's due in part to the well-cast Judd, who lights up the screen all too briefly, and Oliver Platt, as her charming fiance.

(Jim Carrey watchers may be curious about the movie, since he has a tiny part and contributes the opening and closing narration.)

First-time director Johnson (writer of the "Grumpy Old Men" movies) somehow manages to make some of Irving's off-color humor seem smarmy (especially the bits about the boys' curiosity regarding the female anatomy).

"Simon Birch" is rated PG for profanity, use of vulgar slang and some sexual innuendo and violent roughhousing and sports violence (the line-drive accident).