Database Image Error

I have a table which store the pdf in a blob field. On my form field i have set it up the field on list and edit as file and pointed to the filename. Most pdf images open fine but several come up with a corrupt message in adobe pdf reader. I can open the same image fine through our host application using adobe pdf reader. Any Ideas? <img src='https://asprunner.com/forums/file.php?topicimage=1&fieldname=question&id=8529&image=1&table=forumtopics' class='bbc_emoticon' alt=':huh:' />