MY DDJ SX2 FREEZES

My DDJ SX2 keep freezing after djing between 10mins - 1hr, it freezes for like 4-5secs with no sound, and later it picks up and start playing again. Please what might be the problem? I use MacBook late 2009 OS X Yosemite version 10.10.5 Processor: 2.26 Ghz Intel Core 2 Duo Memory: 4GB 1067 MHz DDR3