pdf is either not a supported file type or has been damaged

[sbiese]

We were able to open all of our pdf files until recently. Now, we get an error when trying to open many of the files. If it helps, I viewed the file source with a text editor. A good file has some text mixed with a lot of machine code blocks. When I view the pdf files that I can't open, there is NO text. Only filled solid with machine code (or whatever you call them) blocks. Is there any chance that these files can be recovered?

[Test Screen Name · Accepted solution]

If you have backups, use them, but otherwise this looks gone beyond repair. The first line of any PDF will start %PDF. You have two likely possibilities

* A disk failure is damaging your files. Check your system logs for failures, and check your backup plans.

* A malware attack has scrambled files. If this is confirmed it is best to scrap the system and reinstall to a newly formatted disk.