"Site currently being edited" - cannot log in as Admin all day!

I am the sole Administrator for our iTunes U site, using a new migration to Public Site Manager. Yesterday, all was well and good - I could log in just fine and make updates to the site. However, my computer froze during a Publish process yesterday and I had to restart my PC, and now when I try to log in as Administrator, I get the message "Your site is currently being edited. Please try again later."

When I log in - using the same PC and the same browser and the same URL - with just my Contributor account, I don't have an issue; I can see my feed just fine.

If more info is needed, let me know.

Thanks!