Hi Carl not sure if this help, I have the same stepper drives and run them on XP, they have been fine except occasionally my X axis refuses to go minus, every time I press minus it went plus, I check the signal at the stepper drive plug and it was correct however no movement. After several attempts I tracked it down to a bad connection on the plug into the stepper, I had nipped the wire on the insulation round the wire so occasionally the signal never connected. I realise the chances of this on all 3 steppers is remote but check your connections, even onto the BOB. Just another suggestion have you got the drives earthed, I'm sure when I set up my drives some 4 years ago I had an earth-ing problem but cannot remember if it affected the steppers.
Jim