Perhaps its something not visible in a one-line scope.
Just for fun, try putting an hspace="0" attribute into each of the image tags, see if that helps. (or style="padding: 0px; margin: 0px;")
Also, you've got a width="100%" in the middle image. Some browsers do not like stuff like that, and would always need horizontal scrolling (the image would be 100% of the available width -- say your window width is 500px, if you make the middle image 100%, and the left and right images are 10px, your page would technically be 520px wide).
A different (an my preferred) solution is to use only the left and right images, and in whatever div/table cell you put them in, make the middle image the background.. it will widen (not scale) accordingly.
P.S.:
Please for crissakes, put in the alt="" attribute and title="" if you want a tooltip, and dont forget to close the tag ( ... /> )