Mine does the same thing (although not quite so bad as you describe). I came here looking for help for this problem. I've never tried to take mine back to the store, figuring it was a design issue and that any replacement would have the same problem. Replacing the batteries seemed to help for a few days. I've spent the past 1.5 years trying to figure out how to finagle the thing into doing what I want it to. But I guess I would rather live with the incovenience (and avoid the hassle of replacement!) than get a new fan.