Hi this may not be much help as I don`t use mastercam but I do use alphacam and have had the same problem. My method , although maybe not the best , is I view the tool path closely to see if there are any obvious visible glitches and if I find any then I break the toolpath before the glitch and then it runs fine albeit with a brief pause before taking up the feed again.It is crude but it works for me.
Hope this is of someuse to you.
Cheers Syd