floppy disk not found (40)

I’ve installed a new harddrive and when I connect all other hardware (i.e., floppy disk and cd-rw) I keep getting error messages that say the floppy disk not found and hard disk failure. I’ve tried to switch jumpers on the harddrive, and it seems to detect the harddrive when I don’t have any other hardware connected, but when I connect any other hardware, I get the hard disk failure message. What could be causing these messages. Also, i’ve tried different ribbon cables for the floppy and it still is not being detected?????