There are two width properties you should make sure are set to the same dimensions of your images. Adjusting these to the appropriate size should remove the red line from the CU3ER slider.
1. In the head of the index.php document, there should be a script tag that has “STEP 2” commented out. The “swfobject.embedSWF” attribute should have three numbers, displayed as the following : “370”, “195”, “9”. You need to edit the first two numbers, which are the width and height of the slider, to the appropriate dimensions of your images.
2. Also in the head of the document and within the “swfobject.embedSWF” attribute, an attribute named “cu3er-container” is referenced. This points to the specific CSS style that controls the containing div of the CU3ER. Look up “cu3er-container” in the style.css file, and set the width of that style to that of your images.
These attributes should set the slider and its container to be the same width and height of your images. I recommend visiting http://www.progressivered.com/cu3er/ to learn in more detail about the CU3ER slider.