Redirection bug on a subblog

I created a subblog for our main website, and I never had problems with this in the past, but now with the new subblog every time I’m trying to make any changes (from activating a new template to making/deleting a post!), I’m just redirected to log in page and it won’t let me log back in again. I tried creating a subblog with multiple admin accounts, but the problem persists with all of them. Any ideas how to solve this?