Spring has sprung leaks in big-network lineups. Ratings shortfalls for some top series have sparked Hollywood hand-wringing on the eve of next week's fall schedule announcements. Such shows as ER, CSI: Miami, My Name Is Earl, The Simpsons and Supernatural hit all-time lows in recent weeks, and others -- including Grey's Anatomy and Cold Case -- are down sharply from last spring.

Some observers blame the writers' strike, which forced a three-month gap in most scripted series and led viewers to stray. Most series have trickled back but without the usual marketing fanfare. "I'm not convinced people realized their shows were back," says ABC prime-time research chief Larry Hyams. "It's not like there was a premiere week" that lured them.

Strike-hobbled scripted series weren't the only ones to lose ground. American Idol, Survivor and Deal or No Deal did, too, part of the typical ratings erosion as series age. "There has been significant slippage compared to normal series averages," says ad buyer John Rash of Campbell-Mithun in Minneapolis. "What's difficult to discern is if this is a post-strike media malaise that will be corrected" next fall.

But it's not as if viewers abandoned TV. Nielsen data show overall viewership is flat or up slightly from last spring. Instead, more people are watching cable. And more of them are recording shows on DVRs, now in 24% of homes, up from 16% last spring. More than 2 million Grey's viewers — 10% of its total audience — now watch the show one to seven days after it airs.