Using a PRS-505...
I have attached an epub file that causes the problems described above. For example, If I open the book and page forward, there is a delay of about 4 seconds between each page turn. If I try to jump to another page, the book hangs for several minutes (formatting text at bottom of screen and arrow circling) then reader reboots itself. I've tested 10 different files and have the same issue with almost all of them but only books created from HTML pages.
Would someone else test this and see if you have the same problem?