This is usually a problem only with EBSCOhost eBooks. The easiest solution is to try using a different browser.
If that doesn't work, here's EBSCO's workaround:
To ensure eBooks are displayed in the eBook viewer in the browser window:
eBooks now display in the eBook viewer without displaying individual PDFs for each page.
Note: If you have both Adobe Acrobat and Adobe Reader, you will need to make this change in both applications. This does not work with Apple's Preview PDF reader.