I just upgraded my firefox and was able to confirm the bug. When I try to log in, the cookie just doesn't save for some reason. I have about an hour to look into it before I have to run to an appointment.
OK, wasn't a bug after all. Apparently upgrading Firefox corrupted the DaniWeb cookies. You need to clear all cookies, or at least all cookies originating from .daniweb.com or www.daniweb.com, and then it should work.