Can you post a sample or two?
I looked at the specs and I see that the camera can focus as close as 4cm in macro mode. That probably means 4cm when you have the lens zoomed out all the way to full wide angle, so make sure that you're not getting closer than 4cm, and that you're not zoomed in too much.
You can figure out if it's a shortcoming of the autofocus system by pointing the camera at something with a lot of contrast and texture. All autofocus systems have a hard time with smooth surfaces.
Greg