What is with a lot of threads requiring me to log in to access content. Are these threads locked because when I try to put in my credentials it just refreshes the page?

We get a lot of spam. If the preview is some random article text that contains links to websites, that's probably what happened. Some people request that we close threads or delete posts. Every once in a while, I'll lock threads when they really snowball into trollfest territory. As in some poor OP made some foolish post and is getting hammered for it. Also I'm one of the lazier- err, more conservative- mods and try not to do anything unless it obviously requires action. Other mods are a little more active. We do make mistakes sometimes.