After homing all is fine, when printing the Z-axis stops advancing My Prusa i3 has developed an issue. 

It homes fine and has no issues. But, when I press the print button it gives a sneeze (quick screeching noise from the Z-axis stepper motor) and start to print. The only issue then is that there is no lifting on the layers when it prints! When I kill the print, it stops, lifts and goes to the home position as if nothing is wrong.

Video link: Prusa I3 Z-axis issue

Does anyone know of a remedy for this issue?
Awesome, I got it fixed!

I've restored to default the Firmware EEPROM Settings in the driver program and it's all fine now. I have no idea how that got changed as I would never go mess around there.

I CAN PRINT AGAIN!!

The program I'm using is Repetier. It has a Firmware configuration setting under the printer settings. The values in there was a bit odd so I took a chance and pressed the Reset to Factory Settings and it worked. There is no version number attached to the setting