I decided to go back to the source, so I de-activated the plugin and added jquery.beforeafter manually to the site. My test page contains no code generated by WordPress and I made sure that the two images are the same size.
IE still displays the repeating image. Chrome does not display the image at all, only the "Show only before" and "Show only after" links. Firefox displays the slider effect but has problems with the left/right arrows and displaying the division between before and after properly.
IE8 64-bit v8.07600
Chrome 12.0.742.53 beta-m
Test page: http://d3530684.u264.webdancers.com/test/
I'm not seeing any other reports of these problems, so any help you can offer would be appreciated.