The Tonight Show is a no-show tonight. Host Jay Leno has checked himself into the hospital, and NBC is airing a rerun instead of the planned lineup featuring actor Ryan Reynolds.

Much rides on Leno' shoulders. NBC is saving millions by moving Leno's program into the 10 p.m. slot later this year, sparing it from ordering up expensive primetime dramas. It's hoping, too, that Leno will provide a reliable lead-in to the 11 p.m. news hour at NBC's troubled local stations, which have been hit hard by the drought in advertising by car dealerships.

Leno's unexplained ailment — an NBC flack dismissed one rumor of food poisoning — may be minor; his fans will surely wish him a quick recovery. As will executives. When Leno sneezes, the network catches a cold.