This week: Tim Conway on ‘CSI’; Shania Twain on ‘American Idol’; Sharon Stone on ‘Law & Order: SVU’; ‘The Hills’ returns

Here are words that I never thought I’d write: Tim Conway is guest-starring on “CSI: Crime Scene Investigation.” (The funnyman, right, is pictured with Jennifer Tilly and Paul Guilfoyle in this CBS photo by Sonja Flemming.)

Thursday is the start of the May sweeps, which run through May 26. And the networks will fill their series with major developments and big guest stars.

Conway plays a Las Vegas comic on this Thursday’s episode of “CSI” at 9 p.m. on CBS.

Malcolm McDowell plays a cult leader who matches wits with Patrick Jane (Simon Baker) on “The Mentalist” at 10 p.m. Thursday on CBS.

Will Forte plays the boyfriend of Jenna (Jane Krakowski) on “30 Rock” at 9:30 p.m. Thursday on NBC. Forte’s character has a secret, which NBC has given away in promos.

Before the sweeps start, the networks will load up on new fare this week:

Shania Twain plays mentor to the six finalists on “American Idol” at 8 p.m. Tuesday on Fox. Lady Antebellum and Rascal Flatts perform on the results show at 9 p.m. Wednesday. The six finalists are pictured in this Fox photo by Michael Becker: Aaron Kelly, Crystal Bowersox, Casey James, Michael Lynche, Siobhan Magnus and Lee DeWyze.

Sharon Stone plays the former partner of Stabler (Christopher Meloni) on “Law & Order: Special Victims Unit” at 10 p.m. Wednesday. In one promo, the Stone character suggests they had a close personal relationship.

CBS has new episodes of “NCIS,” “NCIS: Los Angeles” and “The Good Wife” on Tuesday.

On “Dancing With the Stars,” the seven remaining couples will perform the samba or the Argentina tango at 8 p.m. Monday on ABC. Melissa Etheridge will perform two songs on the results show at 8 p.m. Tuesday.

ABC premieres “Happy Town,” a small-town mystery that has been compared to “Twin Peaks.” Yeah, right. ”Happy Town” doesn’t have much of a pulse. Are you in the mood for boring gore? You can see when it debuts at 10 p.m. Wednesday.

Gore of another variety will spread across MTV when “The Hills” returns for its final season at 10 p.m. Tuesday. Take that as your warning.