Same old problem, people buy 320's even though they fault when you sneeze on them.
They trip out at 128 counts, which is easily hit with a sudden move.
What count encoder are you running ? best not to run higher than 250 counts, but then its as coarse as a full step stepper and not nearly as accuarate.
There are a number of far better drives out there that may cost slightly more, but won't send your blood pressure through the roof.
Get a drive that can run a high res encoder and produce smooth fault free motion.