Why does using the zoom function automatically switch to macro focus?

For no apparent reason, when I try to use the zoom feature on my ZS50 (in any mode), it automatically switches to macrofocus, resulting in blurry pictures. Retracting the zoom lens doesn't fix the problem, but if I turn the camera off and then back on again, it takes sharp pictures -- until I try to zoom. In other words, it's now acting like a very nice point-and-shoot camera with no zoom capabilities. I've tried doing a factory re-set and installing new batteries. Is there a known firmware issue, and if so, how can I fix it? Thank you.