Britney Spears has pulled out of a planned guest appearance on Buffy the Vampire Slayer due to scheduling conflicts. "It's not happening," co-executive producer Marti Noxon

tells TV Guide Online. "It's off the plate completely." However, the character Spears would have played will live on, Noxon adds. "We're still going to do the episode, we're just going to do it with someone else," she says, declining to reveal the specifics. "The [story] idea is still valid, and we're going to go ahead and run with it. But now that [Britney's] not available, we're going to push that episode to a little bit later." The pop princess — who is friends with Buffy star Sarah Michelle Gellar — isn't ruling out the possibility of a future appearance. "Britney loves the show, and she'll probably do it one day," says her rep, "but right now, they just can't schedule anything."