Almost any television show goes through growing pains after it hits the network airwaves. Take "Crossing Jordan," the NBC Sunday drama that has survived, and even thrived, despite cast changes, a lengthy, pregnancy-mandated hiatus and lackluster promotion from its own network.

"We really feel that we've hit our stride this season after a couple of rough ones," series creator Tim Kring says of "Jordan," now in its fourth season.

"It's a very happy show, which translates onto the screen. You can feel that as you watch, I think. We've been a little frustrated that we haven't gotten more critical recognition before now, but we're hoping that people will tune in and realize this is really a quality show."

It's also, in many respects, a strikingly different show these days than the one that premiered Sept. 21, 2001, and introduced us to Jordan Cavanaugh (Jill Hennessy), a gifted but tightly wound medical examiner trying to put her life together in her hometown of Boston after a career meltdown in Los Angeles.

Her homecoming reunited Jordan with her father, Max (Ken Howard), a retired cop haunted, like Jordan, by the unsolved murder of his wife. Jordan's own obsessive quest to solve that case threatened to take over her life in the second season, which culminated in a taut cliffhanger.

That's when several factors led to an abrupt change of direction and tone. Among them was Hennessy's wish to let Jordan lighten up a bit.

"Those episodes when Jordan was so obsessed with her mother's death -- I think there are only so many times you can go to that well before it loses both its potency and its relevance, although some of those episodes were very compelling," the actress says.

"It just felt to me that we had taken that to the nth degree and it was time for us to move on. Tim Kring understands that. He's masterful at going to the dark places in a way that few writers can do, but he also recognizes when it's time to move past that."

Kring acknowledges that NBC wanted "Jordan" to emphasize its procedural crime-solving over dark character angst. As it turned out, external issues pretty much decided the matter.

For one thing, Hennessy became pregnant and needed to take off the first half of the 2003-04 season. Another complication: After filming the first part of the second season cliffhanger, Kring learned that Howard, a key player in the cliffhanger, would not be returning as a regular in the third season.

Eventually, Kring and NBC executives decided it would be in the best interest of the show to reinvent itself to some degree when it returned after nearly a yearlong absence.

"We did it for lots of reasons, mainly because we were going to be off the air for 10 months," Kring explains. "Coming back on a new note, as we were trying to get new viewers, it seemed that we were better off just telling stories about cases that could be solved so, as a new viewer, you didn't feel that you had missed something.

"The network -- and I think rightfully so -- chose not to air the cliffhanger resolution as the opening episode. We took a lot of flak from our loyal viewers for doing that, but I absolutely still believe that was the right decision. Certainly we would not have gotten a single new viewer to the show by airing that resolution when we came back. I wrote [that script] and three months later, I couldn't tell you what was going on: people talking about names, faces and people who were no longer on the show."

The gamble paid off. Moved to a higher-profile Sunday time slot and paired with "Law & Order: Criminal Intent," "Jordan" suddenly zoomed in the ratings.

Kring says, "While we were off the air, all those dry procedural shows began to wear on the audience, and when we came back with a lot of character-driven stuff, the funny banter between characters, we seemed like a breath of fresh air."

"We seemed like a new show that came onto the air fully formed," he says. "Shows take a while to find themselves, as a rule, and people who tuned us in for the first time when we came back saw a show that was very slick."

Both Hennessy and Kring are quick to give credit to cast member Jerry O'Connell for much of the new energy that now drives the show. O'Connell began occasional appearances as Boston Police Detective Woody Hoyt in 2002 but became a series regular this season.

"I've always liked Jerry O'Connell," Hennessy says. "In addition to being, uh, hot -- I mean, he's a total dish, and you've got to see his body, which is just spectacular -- he has such a facility with both comedy and drama.

"On a fundamental level, having a strong actor who's also comedic in the role of a detective helps immensely. In regards to the whole feasibility of the show, let's face it, you can't have a medical examiner investigating crimes. It doesn't work and it isn't realistic. So we needed a pivotal character in the cast who could get into a crime scene and pursue an investigation and have Jordan take a part in that. Otherwise, it would just be too hard to swallow, with Jordan breaking into police headquarters and stealing evidence."

O'Connell's presence also opens up potential for romantic comedy in the show's story lines, something Hennessy says she relishes.

"The character allows Jordan to show different sides -- vulnerable, romantic, kooky -- which is great, but the audience also responds so well to the procedural stuff we do together," she says. "I'm just so glad he finally signed as a regular, because I would probably jump off a bridge if he left."