"Scrubs" (9 p.m., NBC): Always silly and inventive, "Scrubs" outdoes itself with this week's episode of the NBC comedy: a full-blown musical set at Sacred Heart Hospital. A woman arrives at Sacred Heart complaining of hearing nonstop music and (funny thing!) while trying to determine the cause of this strange affliction, the "Scrubs" cast does seem to be in constant song. The sassy songs were written by the Tony-winning composers of Broadway's "Avenue Q," Robert Lopez and Jeff Marx. Stephanie D'Abruzzo, an original "Avenue Q" cast member, guest stars as the music-beset patient.
"CSI" (9 p.m., CBS): "CSI" fans, please give a warm welcome to Liev Schreiber. The talented actor joins the cast as a veteran investigator who takes Grissom's place while the head guy is on sabbatical. As you might expect, the Las Vegas detectives need some time to get used to him.
"Ace of Cakes" (10:30 p.m., Food Network): Cameras shadow a chef who takes blowtorches, drills and saws to make his creations for a second season. Sounds yummy, doesn't it?