Evidently, "perky" and "likable" aren't what the nation's network news watchers want with their nightly dose of headlines. This is a tough (and expensive) lesson being learned by the folks at CBS Corp. (NYSE: CBS).

Last week, the CBS Evening News, which has been anchored by Katie Couric since early September, attracted its lowest ratings since 1987. During the first week of May, which happens to mark the beginning of the television industry's spring "sweeps" period, an average of 6.05 million viewers tuned in to watch the former Today host deliver the news. Couric is currently the highest-paid news anchor, at $15 million per year.

ABC's World News offering, meanwhile, averaged 8.1 million viewers, while NBC's Nightly News saw 7.5 million viewers tune in. Charles Gibson mans the desk at ABC -- a division of Walt Disney (NYSE: DIS) -- while Brian Williams is the weeknight anchor for General Electric's (NYSE: GE) NBC.

Thank goodness for the CSI franchise and other programs that keep CBS moving at an enviable clip. The network still won the week, earning an average 11.2 million viewers in prime time to top its four competitors.

How do you solve a problem like Katie? According to recent theories from "CBS sources," she may gracefully bow out of her current role following the 2008 Presidential election and take on another position at the eye network. But even that is well over a year away, and there is the potential for plenty of sub-par ratings between now and next November.

Beth Gaston Moon is an analyst at Schaeffer's Investment Research.