if you have Chameleon installed on the snow partition, use Diskpart in windows. if you don't no how...

PS: i have dual boot on same hdd , diff partitions with win7 and leo...but chameleon is installed on an usb stick with the needed extra folder and it's set from bios to boot the usb stick first.

open a commander terminal (win+r...type cmd...hit enter) and type:
->diskpart
->list disk
!!! if you have more than one hdd select the hdd on with is installed snow
->select disk $
!!! $ is the number of your disk, i have disk 0 and 1...in my case is select disk 0
->list partition
->select partition &
!!! & is the number of your snow partition
->active
!!! if it says that "active" is not recognized type "set active"

now reboot and you should be able to select snow or win