PDFs Have Suddenly Stopped Displaying

[agaluski]

You can have the same error if you have a blank line BEFORE the <?php at the top of a script.
For example. I just opened includes/session.inc. Went to top of file. Hit enter, saved it and broke all my PDF's with the same error.
So check the list of files Tim Mentioned to make sure non of them have leading blank lines in the file.
Also - when you check error logs - which logs are you referring to. What level is PHP set to, no error, warning, etc?