i have same exact error
i know its not browser cache because another admin also got same error and he is in another part of the world.
the message that pops up is "To continue this action, login using the admin account that initiated the action" and gives a login box and its completely random.
Sometimes when I click Submit button in admincp for any option it completes successfully. At other times it throws me the error with the login box and I enter my admin user/pass and it then completes the initial submit task successfully .. or otherwise it brings me back to the same login box again with same error ... and some times this process can go on for 10-15 times before it actually submits ..
its very very annoying