Troubled pop star Britney Spears was stopped by police in Los Angeles on Monday (29Oct07) - after her Vehicle Registration Tag expired. The Toxic hitmaker was leaving nightclub Winston's in the city on Monday night (29Oct07) when she was handed a warning by officers. Spears' pal Alli Sims was overheard telling officers, "We'll get one this week, she just got this," reports website The 26-year-old already faces charges of driving without a valid California licence and earlier this month (18Oct07) ran over a videographer's foot.