Access to Admin login page suddenly gone; circular redirect!

[Nyssa]

Help!!? In Firefox I get "Problem loading page: Firefox has detected that the server is redirecting the request for this address in a way that will never complete" instead of admin-login page. In IE8 the lower left corner flips rapidly between "found site http ..." and "searching for 208 ..." where you can actually watch the unresolvable circular argument.

Zen has been working perfectly (and not upgraded) since early '08. This just started, and I'd made no changes either to Zen on the server or through admin (which worked fine last Friday), nor even anything as invasive as a recent backup.

I have several domains hosted in sub-directories under one root directory. The only possible correlation I can think of was a Drupal install/uninstall/reinsatall over the weekend on another in another same-tier directory.

[kobra]

Check your ZenCart files for date modified and look for any recent modifications

You might have been hacked