Login Error – Repeated requests

When I login to my blog, the dashboard begins to load and is then corrupted by an overlay of the login screen. Refreshing the page takes me back to the login screen, where the cycle begins all over again.

If I do manage to get past the dashboard and into say, “Manage”, I am taken back to the login screen. After logging in, I am taken to the “Manage” area, but click on a link and it’s back to login.

Please advise.