When a television show hits 100 episodes, it's usually considered a time for raucous celebration. But the NBC hospital comedy "Scrubs" has never really done anything the conventional way and isn't about to start because it has achieved "this weird, artificial milestone from days past," as creator and executive producer Bill Lawrence puts it.

Those associated with most series would toast the TV gods for having bestowed upon them such good fortune, but the "Scrubs" gang -- though clearly pleased for the opportunity to see a 100th installment, set to air tonight at 9:30 -- uses words such as "weird," "shocking" and "confusing" to describe the feeling, especially because this group has always felt a bit underappreciated.

After all, here is a series that has been stuffed into seven time slots in barely more than four seasons, and Lawrence has not been shy in noting that TV critics have been more consistently supportive of "Scrubs" than has been the network that broadcasts it. But NBC continues to order episodes and keep the sitcom on the air -- though it did not return for its fifth season until Jan. 3 and will air 24 new episodes through May.

Not that Lawrence is complaining about the midseason return -- at least, not much. He can't, really, because "Scrubs'" fifth-season premiere delivered a reasonably healthy 3.8 rating and a 9 share among adults 18-49 and 7.7 million total viewers, while Episode 2 -- which aired the same night -- earned a 4.0/9 in that key demographic and 7.8 million viewers.

"I hate to admit it, but the midseason start turns out to have been a pretty good move for (NBC Entertainment president) Kevin Reilly," says Lawrence, previously a writer and executive producer on the 1996-2002 sitcom "Spin City." "We came out of the gate with really solid numbers this month; the simple fact that the show hadn't been on for a long time seemed to have whet a lot of appetites. Seeing people root for and write about us is kind of a pleasant surprise; our very Internet-savvy, high-end, psychotic geek audience has really come through for us."

Adds Zach Braff, who stars as intern-turned-resident John "J.D." Dorian: "What Bill says is true about our audience: They've been there for us, and they're loyal. I only wish more of them had Nielsen boxes."

During the 2004-05 primetime season, "Scrubs" averaged a 3.1/8 among adults 18-49 and 6.9 million weekly viewers -- not exactly record-breaking numbers, but good enough to be the campaign's top Tuesday comedy among adults 18-34. The reward was a ticket to midseason for 2005-06, which has not turned out to be a bad thing but nonetheless felt somewhat like a slap in the face to those involved in a series that would receive four Emmy nominations last summer (including long-awaited firsts for outstanding comedy series and for Braff as lead comedy actor).

One might excuse these fellas, then, if they don't fall all over themselves with gratitude upon marking "Scrubs'" 100th installment. As Lawrence notes, getting to triple digits in a show's episodic life "used to mean giant syndication dollars. Not anymore: Now, all it means is that you've been around for five seasons, you're old, you have children, your life is going nowhere, and you can no longer reinvent yourself."

Ah, but there, he might be mistaken. There is strong talk that "Scrubs" could be heading to ABC after this season, which would only make sense given that it's a Touchstone TV production and therefore an ABC cousin under the Walt Disney Co. umbrella.

"I wouldn't be surprised if we wound up there," Lawrence says. "The president of entertainment at ABC, Steve McPherson, basically developed our show when he was running Touchstone. I'm confident we'll come back for a sixth year, but let's face it: We're a hindrance to NBC because it isn't a profit participant like ABC would be. We're a dinosaur-to-be on one network and completely owned by another. That's why it's so shocking we've survived to this point, depending as we are on the good will of a network that has so little to gain with us. I mean, I wouldn't put us in a plum time slot, either."

But Reilly does not sound like he wants to send "Scrubs" to the competition.

"'Scrubs' has always been so well-produced," he says. "It has had to travel a twisty path, in terms of time period, but has been a feather in NBC's cap as one of the most inventive shows on television. It goes from absolutely broad, insane silliness to poignancy and sweetness so seamlessly, the cast is phenomenal, and Bill Lawrence is not only a funny guy but (also) an expert at handling an unbelievably tough single-camera schedule."

Lawrence has kept it all together on a show that, through no fault of its own, began ominously. "Scrubs" debuted Oct. 2, 2001 -- three weeks after the Sept. 11 terrorist attacks -- and hung in during a period in which the American viewing public did not feel much like laughing. Perhaps that timing was in keeping, though, with a series that has been an overachieving underdog from the get-go.

A creative blessing but perhaps a mainstream curse for "Scrubs" has been its quirky sensibility, replete with odd flashback sequences and even the occasional production number. Set in the surreal Sacred Heart Hospital, the series began as a weekly tale related through the eyes and experiences of rumpled young intern J.D. Dorian, who since has evolved -- like the actor playing him -- into a more seasoned resident.

Surrounding J.D. is a motley cast of doctor characters, played mostly by previously unknown actors, that includes resident Chris Turk (Donald Faison), J.D.'s college buddy; beautiful but socially awkward Elliot Reid (Sarah Chalke); abrasive but good-hearted Perry Cox (John C. McGinley), and cynical chief of medicine Bob Kelso (Ken Jenkins). Also onboard are the all-business nurse Carla Espinosa (Judy Reyes) and J.D.'s unlikely nemesis, the hospital janitor (Neil Flynn).

"All I feel is tremendously lucky," Braff says. "We've had a harder run than most shows in making it to 100 -- it's weird when you feel like you're barely hanging on to your time slot -- but that doesn't diminish from it at all."

McGinley arrived at his newfound success from the other side: as a long-unheralded and -underrated character performer (he has appeared in more than 60 films) who seems to make everything he's in better. His work on "Scrubs" has drawn major raves from critics, and while it has not resulted in what would be a much-deserved Emmy nom, it has put McGinley on the map at long last.

"To say I have loved every second of this would be a major understatement," McGinley says. "It has upped my profile hugely, partly because I've received all of this hype for Emmy Awards and keep not getting nominated; I think being passed over has actually served me better because it has gotten me more press, ironically. But, all in all, this show has been a revelation for me personally."

That NBC had to find a time period for "Scrubs" this season, after it received a two-year renewal before Season 4, might have meant that the series felt like an albatross to the network -- but it further fueled the "us against the world" mentality shared by the cast and production team. McGinley also believes that the top-comedy Emmy mention, coming as "Scrubs" was being put off until midseason, "really put some wind in the sails of our writers."

All Chalke knows is that her role is easily her best to date -- hardly a surprise, considering that the Ottawa native is all of 29.

"But I think I'd feel that way even if I were a lot older and more experienced," she says. "I'm definitely spoiled for the long haul, I'm afraid. To be involved in a show with such amazing writing, that has such a great balance of comedy and drama and deals in real issues as well -- like the drama of losing patients -- I mean, as an actress, you just never get tired of that. Then, to get to work with people you actually get along with and want to hang with -- it's just so rare."

Lawrence knows all about taking the bitter with the sweet -- sometimes simultaneously --when it comes to his medical comedy. He cherishes his creative independence on "Scrubs," even as he rails against what he sees as a flawed Nielsen Media Research ratings system.

"We have always had to exist in this weird netherworld between a giant hit and a critical darling," Lawrence says. "We've landed smack in the middle: never ratings-challenged enough to have people rally for us, like they did for (Fox's) 'Arrested Development.' We haven't found ourselves in truly dire straits, so we never get the 'Why We Need to Appreciate This Show More' articles in Entertainment Weekly.

"On the glass-half-full side, we're still alive and kicking," he adds. "NBC is sticking with things they believe in, like 'The Office,' longer. And they've stuck with us when they didn't have to, when it might even have made more sense if they hadn't. So life is pretty good -- I don't really have much to complain about at the end of the day. Unfortunately, that doesn't make much of a quote."