Reviewed by GREG KING Director: Tamra Davis Stars: Britney Spears, Anson Mount, Dan Aykroyd, Taryn Manning, Zoe Saldana Part Boys On The Side, part Coyote Ugly, and one part just plain ugly? While not quite the dog we were all expecting after fellow singer Mariah Carey's dire debut in last year's awful Glitter, teen pop sensation Britney Spears' highly anticipated film debut Crossroads is still …