ProTools distortions
 

Hello, when I play a session that have some audio files, frequently this distorts. I have to quit and restart PT, but many times it does the thing again.
I'll appreciate any advice. Thanks

Mac Mini (Late 2014) 2.6 GHz Intel Core i5
Memory 8 GB 1600 MHz DDr3
OS X Yosemite Vers 10.10.2

Protools 12.0.1
Focusrite Scarlett 6/6