Dropbox won't show my pdfs properly

It's been about 10 days that Safari seems to have a problem with Dropbox.

Problem is this: I run a webiste and I link my pdf files to my Dropbox account (visitor clicks on a photo and gets redirected to Dropbox to get the pdf). Ten days ago, everything worked ok, now ALL my pdfs look like this

Yet, when I downloaded some of them, they are ok and only SEEM to be ruined. I already contacted Dropbox Support and replied to me that this is not something they can do about it, since everything looks as it should when I use Google Chrome! Here is a snapshot of the document above as it should appear (shot taken using Chrome).

(It's in greek, don't bother trying to understand it, unless you're Greek, lol).

Why is this happening? What's wrong? I haven't messed up with any of Safari's preferances. Oh, by the way, a friend of mine was seeing everything ok in his Safari, while another one no (in Safari as well).

Thank you in advance!