Id remove the slave and make sure the jumpers on the master are set for a single master use (some bios's wont accept its there otherwise)

and see if itll boot up from the single harddrive, try swapping the master with the slave and botting the previous slave drive as the master, if the primarys gone bust the slave wont do anything either so you might be able to salvage that as your main drive until its sorted. if that doesnt work and you have any spare ide cables swap them round incase thats it