I’ll be honest, I don’t think I’ve ever had this problem with Reddit. I do know people it has happened to though. Not me though. Still I did have a Digg incident a while ago. You know back when people still used Digg.
You see, a couple years ago the server started getting hit really hard from their site. Someone had linked to the This is PORTAL! comic and it was becoming very popular. Unfortunately, they had only linked to the actual comic image file and not the page itself. So the site got all the stress of additional CPU load on the server, but without the benefits of any additional website traffic.
The only saving grace was that the URL and copyright information were still on the image file, so at least I didn’t have to worry about not getting credit for it.