It can happen to anyone, really. From time to time I try to go through any sites I link to, and when I find them down (that is, accessing it gives an error) for some time, I will add a text saying so.

Since the address of removed sites become available to use for anyone and I don't want any unpleasant surprises with what the future owner of that web-address plans to do with it, I'll unlink the sites if I'm confident they're down, however still leaving your logo on the site. Even though I would most likely not remove it anytime soon in that case, it would be kind if you told me your new web-address (if you have one), so I can bring the section up to date and relink you.