I have had this same issue when creating a with 3 slider images. Each one of the images has a gray bar to the right. I checked the sizes against the originals on my computer and it seems that it is the sliders placeholder box showing from behind. The images are 600 X 101 but they are getting reduced down and showing the grey box behind. Any Ideas on how I can fix this.
Update: Found a work around until I can figure out a true reason this is happening.
I figured out that it was the slider image in the plugins folder.
Plugins/Promotional-Slider/CSS/Images
I just changed the name for now so that it does not show up. Later I will just create an empty file to use in its place.
