Customer on PC experience issues with Digital Editions. Page is all jumbled up, no single page view.

Hi all,

I would appreciate some help in helping this customer. She has multiple purchases from us that are all ePub files, however for one of them only she is experiencing viewing issues and has shown us a picture of the page all jumbled up. She says it happens on all pages in that publication only. She is the only customer with this problem which makes me think she has changed some settings but I can't figure out which ones. She also reports that on her PC there is no 'single page view' option. I don't have a PC but I can find it on my Mac version of ADE. Anyone got any ideas?