Sometimes you can get a message disk error and it could be the actual floppy. They don't last forever.
Another option is to use midi cables and download http://www.midiox.com/ you can transfer sequencer, program, combi etc through midi-ox. On the Korg X3 hit the Global button and scroll to Midi Dump change program to sequencer, open midi-ox, Click options and make sure you have midi device selected. ( I use A Roland Dual Capture ExGo Interface, my midi cables go from the Korg X3 to the back of the interface) to View, scroll to Sysex, a new window opens up. You can Send sysex file under File or you can go to Sysex receive manual dump, you will see a bunch of numbers come through , wait until its finished and it will say Done, Click Done and on Midi-ox, go to Display Window and go down to Save as