When saving either programs or samples, on occasion the S6000 goes through the motions of saving, but when the material is recalled, the save has obviously not happened. Is there a reason for this? The machine otherwise works perfectly.

The problem here is caused by lack of space on the hard drive. It occurs when the hard drive you are saving to is nearly full (about 1 - 200Mb left). The S6000 gives no indication that there is a problem, but the material is NOT saved. The solution is to free up some space on the hard drive by archiving or shortening samples, or getting a bigger or second hard drive.