Hi,
You may want to read the following thread here on Mobileread:
https://www.mobileread.com/forums/showthread.php?t=62558
Most page errors from epubs that work well on the PC but not on Sony come from the fact that the epub was not created following best practices guidelines.
Mony mobile devices (Sony included) have space limitations for unpacking the html document that is the book content inside the epub file. According to Adobe, best practice is to limit the size of any one html file to be less than 300k bytes uncompressed and 100k bytes compressed.
If the book you have does not have DRM, you can simply run unzip to look at what is in the epub. Looke for .html files that are too large. That is the issue.
If there is no DRM, you can use Sigil to read in that epub and add a chapter break or 2 (or many) to split the html file into many smaller html files (typically one or even more for each chapter). Then use Sigil to recreate the epub and it should view fine on the Sony reader.
If it has DRM, then you should return the book explaining about the issue or use one of the scripts out there to remove the DRM and fix the book yourself.
Lots of people make epubs with one big html file in it which makes the device either give an error or makes it so very very slow to open when it does try to read the file.
Following best practices for epubs, is the right answer.
Hope this helps,
Kevin