Flickr issues?

So... Our photo hosting site seems to be having some issues. The thumbnail images of our sets and links are not the photos we've uploaded (i.e. they are someone elses pictures). Some of them are not-so-nice. So, if you've been to our site(s) and seen something nasty (I have), please be aware that it is an error with Flickr and not a picture we posted!! Yikes.