"Mad About You" (7 p.m., NBC/Ch. 5) opens its seventh season by breaking down yet another prime-time network barrier. If memory serves, this is the first time that a lead character in a sitcom has spent most of the episode walking around in a state of sexual arousal.

How proud Paul Reiser and the "Mad About You" team must be.In the episode, Ira (John Pankow) convinces Paul (Reiser) to take a Viagra pill - the impotency drug - from a prescription he lied to obtain. Paul resists but - at the urging of his wife, Jamie (Helen Hunt) - he finally takes one.

Which is how he ends up wandering around Manhattan frightening guest star Jerry Seinfeld, drawing plenty of attention to himself and bumping his, um, anatomy up against people.

I am not making this up.

Jamie, meanwhile, is wandering around Manhattan dressed only in a towel after she gets locked out of her health club. But she and Paul eventually reunite in time to, um, take advantage of the Viagra.

While not especially salacious, this episode does demonstrate a certain desperation on the part of Reiser and NBC. This past spring, the network agreed to pay both Reiser and Hunt a million dollars an episode to do another season of "Mad About You" - just in time to see the show's ratings sink behind those of both CBS's "JAG" and ABC's "Home Improvement."

And, of course, it raises the question of what if anything remains out-of-bounds for a broadcast network sitcom that airs at 7 p.m. Apparently, very little.

What makes this particularly interesting is that "Mad About You" airs on KSL-Ch. 5, the same station that refused to air "Stressed Eric" this summer because of its crude and vulgar content. (Which it did indeed contain.)

But in "Stressed Eric," nobody wandered around bumping their, um, anatomy into people.

It was fairly easy to yank a summer series that NBC will never air again. The real test of KSL's commitment to upholding its broadcast standards comes at times like this.

And the viewers are doing the grading on this test.

"NEWSRADIO" STRUGGLES: The NBC sitcom "NewsRadio" has a deep hole to dig itself out of this season. The death of Phil Hartman cost the show dearly - both in terms of the loss of a co-worker and the loss of the one man who could be counted on to deliver a laugh almost anytime he was called upon to do so.

The show tries to deal with his death in its fifth season premiere, which airs Thursday at 8:30 p.m. on Ch. 5. The absence of Hartman's character, pompous newsman Bill McNeal, is explained - Bill suffered a heart attack while sitting at home watching TV.

We see the aftermath of his funeral, at which Dave (Dave Foley) apparently delivered one of the all-time worst eulogies in the history of the world. And we learn that Bill left personal letters for all of his co-workers, to be read in the case of his untimely death. Even former series co-star Khandi Alexander returns.

But the problem is . . . this has to be the single worst episode of "NewsRadio." Ever.

It's not funny, it's just uncomfortable. It's not touching, it's just uncomfortable. And it's very uncomfortable.

If this is what the show is going to be like without Hartman, then perhaps the producers and NBC should have just folded up their tent and moved on.

However, it's probably too early to write the show off. This was an episode that had to be made to provide some sort of closure for the fans. And we won't really be able to tell whether "NewsRadio" is salvageable until the second episode, when Jon Lovitz joins the cast as the new newsman at the station.

Let's just hope that "NewsRadio's" second episode of the season is considerably better than its first.