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.