This problem just started about a week ago. In the middle of a program the x-axis moved about 30" off. That is when we noticed the grinding noise. It is intermittent also. Below is a link to a video I took. At about the 47 second mark it starts operating properly, and then goes back to making the noise at about 1:17. Any ideas?
http://www.youtube.com/watch?v=hJpHARIpjBE