Call from a customer who is using one of our scan storage servers:
"Some of the reports on the server are corrupted, they won`t open in Acrobat"
Talked hinm through checking the backup, seems that those files are corrupt too.
Travel out to the site.
Turns out the operator scanning the reports had mistakenly scanned the files as TIFFs, instead of PDFs, but to avoid rescanning them, he had renamed them as report.pdf