Do you have "hide viewed posts" checked? I don't think that is the exact wording, but it will hide posts that you have opened, commented on, voted on, and also the posts you have created.
AHA! That's it but I see why I had it set the way I did. At least in the interface I'm using I read it the way you suggested as "hide viewed posts" so I unchecked it but it's actually "show read posts." Basically opposite functionality from when I had glanced at it and thought I understood. Thank you!
i think the servers are a bit wonky at this time due to the influx of new users. there will probably be stability issues for a few weeks until things normalize. you can try clearing your cache? that might help.