After recording its first week-to-week uptick in ratings last week, NBC’s highly touted drama “Studio 60 on the Sunset Strip” dipped to a series-low for last night’s episode, erasing all of the previous week’s gains and then some.

The 10 p.m. show averaged a 3.1 in adults 18-49, according to Nielsen overnights, down 18 percent from last week’s 3.8. It was also down 9 percent from the show’s previous low, a 3.4 on Oct. 2.

“Strip” dipped to third place in the timeslot, behind ABC’s “What About Brian,” which was up week to week from its premiere.

So what’s the problem with “Strip?” Though certainly one issue, already raised by media people, is that the show is too inside Hollywood to draw non-media junkies, it may also be that the show’s quality is sliding.

After an excellent pilot, the show has slumped into inertia of sorts, with a love story that doesn’t go anywhere and no overall plotline giving the show urgency. Another issue is the writing for the show-within-a-show’s comedy sketches. They’re rarely funny, and they take up too much of the program’s time.

Certainly all new shows go through ups and downs creatively, and though the stories may have faltered, creator Aaron Sorkin still offers crackling dialogue. But this latest ratings downturn is certainly not good for a show that media people already tabbed the year’s most disappointing in a recent Media Life poll.

Yet it’s worth noting that NBC still won the night among 18-49s, its fourth victory in five weeks, thanks to the strength of its 8-10 p.m. lineup of “Deal or No Deal” and “Heroes.”

Meanwhile, things looked much better at the CW, where its revamped Monday lineup debuted to much stronger ratings. The four-sitcom block was up 15 percent among 18-34s over the most recent original episodes of former timeslot occupants “Seventh Heaven” and “Runaway.”

The CW averaged a 1.5 on the night, and every show was up at least 17 percent over its first two outings on Sunday night.

NBC finished first for the evening with its 4.7 rating and 12 share among 18-49s, followed by CBS at 4.5/11, ABC at 3.6/9, Fox and Univision at 1.5/4 and the CW at 1.3/3.

ABC’s ratings may change when final numbers are released later today, as its Monday line-up was pre-empted in the Chicago market for the Chicago at Arizona ESPN “Monday Night Football” game. And at 8 p.m., ABC's “Wife Swap” was pre-empted in several markets for local political debates, including Detroit, Grand Rapids, Harrisburg, Flint, Green Bay, Syracuse and Cedar Rapids.

At 8 p.m., NBC’s “Deal” led at 5.2, followed by ABC’s 3.6 for “Swap,” CBS’s 3.2 for “How I Met Your Mother” (3.4) and “The Class” (3.1), Univision’s 2.0 for “La Fea Mas Bella,” Fox’s 1.5 for a “House” repeat and CW’s 1.3 for “Everybody Hates Chris” (1.3) and “All of Us” (1.3).

At 9 p.m., NBC’s “Heroes” remained steady at 5.7, followed by CBS’s 4.7 for “Two and a Half Men” (5.2) and “The New Adventures of Old Christine” (4.2), ABC’s 3.7 for “The Bachelor: Rome,” Fox’s 1.6 for another “House” repeat, Univision’s 1.5 for “Mundo de Fieras” and CW’s 1.4 for “Girlfriends” (1.5) and “The Game” (1.3).

At 10 p.m., CBS’s “CSI: Miami” led at 5.6, followed by ABC’s “Brian” at 3.5, “Strip” at 3.1 and Univision’s “Cristina” at 1.1.

Among households CBS led with an 8.9/14, followed by NBC at 7.8/12, ABC at 6.2/9, Fox at 3.1/5, Univision at 2.0/3 and the CW at 1.9/3.