Sorry...wasn't trying to insult you....there's just people of all abilities on the forum and sometimes the simple, obvious solutions are overlooked.
Again, nothing personal intended.
Have you eliminated the possibility that it's a bad PDF file?
In other words, you can open up other Acrobat files on other sites and you can open up this pdf off your desktop, but when opening the same pdf file through your website, it results in gibberish...