Hi Robert, yes we have also had this problem (about 30%), but only with the wgt3xbt accelerometers. The older versions work well still. Currently we have stopped using wgt3xbt until the problem is resolved, as clearly this is not an acceptable data loss rate for research.

Ross, thanks for the answer. Apparently Actigraph came out with updated firmware yesterday that should resolve the problem. In communications with Actigraph they kept telling my that our lab was the only one in the world that was experiencing this problem, which I found hard to believe.