Audio Importing Adds Noise Artifacts

Hello, everyone. I am hoping to find out an answer to a question about a very discomforting situation. When I import audio from an another studio or from my own other computer, which hosts Reason, somehow noise artifacts appear on the tracks, although there were none in the files. The look and sound like clipping. Absolutely random position. Sometimes a single one, sometimes a whole bunch of them like a rifle shooting. Both on silence and on signal. What might be causing this problem?



I am using PT8 with Eleven Rack plus Macbook early 2011 with Mountain Lion but no Mavericks installed.