ipad2 ibook glitch

[Aikuchi]

I have a friend with a ipad2 and she has a few side loaded e-pub books in ibook. Lately she has been running into some glitches. First when turn a page, it doesn't matter witch edge you tap on it always turns from right to left. Second when you tap on a link that goes to another page in the book it always goes two or more pages from were it should be. Last the link at the bottom of the page that says "return to page ###" has disappeared.
I have google it but I haven't found any solutions for these glitches. Also she doesn't want to do anything that would wipe out app data, she has a lot highlights and notes in here books that she doesn't want to loose. Any help would be appreciated, thanks.