Might be a problem with the epub. I had created a few epubs where they would open in the Calibre viewer without issue, but load on to the PP and the last page I could go to was 2/3 into the book. Converted the files (at the time) to both .mobi and .fb2 and the files opened without issue.
For me I think the problem was during the conversion either some non-standard characters or non-standard formatting tags were used during creation of the epub. I revisited the problem at a later date and found if I did the conversion through eCub it worked flawlessly, so my experience was that Calibre was doing something funny.
You could always test by converting your html to epub using eCub (http://www.juliansmart.com/ecub
) and see if that fixes your problem.