Track grinds to a slow speed and quality degrades

So I’m using DJay Pro on a windows 10 laptop with a Pioneer DDJ-SR Controller.

Windows 10 bang up to date and so is the firmware on the controller.

No problems for first few months. Did a gig last night and about 2 hours in the track on the right deck just slows right down, and the sounds becomes distorted.

The only resolution was to shut down DJay Pro and reboot the controller, NOT ideal when you have 50-60 people dancing away and then be presented with silence!

Any ideas as to why this might be happening and any fixes would be great.