Is that KK01 the same sort of card that's pictured here:
https://www.cnc4you.co.uk/Breakout%2...xis-with-Relay
OK, so with all the Leadshine DM2282 drivers connected to the KK01, but the all the motors disconnected at the driver end, it works OK. Connect them both and it looses USB access; which I suspect is how your keyboard and mouse are connected, right? And without a functioning keyboard and/or mouse, it appears that the whole CPU has frozen? (I'm suspicious that the CPU & Windows is running OK)
Have you tried connecting only one motor, and then the other to see if you can localize the problem?
How is the wiring going from the PC to the keyboard and mouse; and the wiring going from the PC to the breakout board, to the stepper drivers, and to the motors physically arranged?
I am suspicious of this being an EMI (Electro Magnetic Interference) problem... either something broke (shielding wire, filter of some sort, etc) or it was always marginal but now it's gone over the threshold of not-working.