I assume that you used grub2 as your bootloader for aptosid. The given boot entry is from your opensuse installation?
Did you install your aptosid bootloader into the MBR (master boot record), or into the partion? If you installed it into the mbr, it was overwritten by the opensuse grub. If that's the case, you have to add a grub entry pointing to the actual kernel and initrd:
kernel /yourkernelroot=/yourrootdevice vga=773 ro
Remember that grub numbers devices beginning with 0. So if you installed aptosid onto your first hard drive, you have to refer to it as (hd0,sthsth)