It can't be disabled, as you can see it. To disable it you need to go to the early boot menu (hold both mouse buttons on startup) and deactivate it there for the actual session only.
It must be a problem with the floppy itself, either cable, de-adjustment or dirt, or the aforementioned little capacitor on the drive leaking.
If you have an external second drive try this just to make sure the fault is not in the chipset on the motherboard.
