Guests can no longer post links...?

We haven't changed anything with the forum, and I'm pretty sure neither of us (the two admins) has even been in the admin panel in forever (except recently to try to figure out the problem) but for some reason the forum isn't allowing guests to post links anymore. They used to be able to, and then one day, they couldn't... does anyone know why? or how I can fix it to go back to allowing guests to post links?

And no matter how they try to post links, it doesn't work. A simple copy and paste of a url, using the link button, nothing works. It shows up as they're typing their post, but after they hit send, it's not there in the posted message.

Help!

What code do they use?

I apologize in advance if I come off ignorant...

do you mean BBCode or HTML? if you do, then BBCode

thank you

Nopes, the basic code what does it contain. Whatever it is, what is it?