Hi there Mel,
I created a new user under the Stack Ideas name as a Registered user group. So far I am able to view as well as create blog posts without a problem as you can see here:
http://screencast.com/t/0Op9M0OxysS. I've even changed the support account to only Registered and it worked fine.
Can you perhaps try and and set back the non-superusers account to other user group levels and test it again? If the issue still persists, can you screenshot the error? It would be most helpful to us.
Hope to hear from you soon!