I've had the issue before. I was able to right click the file, open it using RAR (also, might want to unclick the box that makes that your default opener) and renaming the pages. This solves the problem made when someone names the front cover "fc" but then names each page numerically and the program then wants to show "1" through "64" before it'll show "fc". I renamed "fc" to "0" and it became the first file retrieved numerically.