This is really odd... I have had a website running for someone for a few months, I haven't changed anything on it for a month or two, and now when I go to the /admin I type in my log in details, and it seems to be doing something, then just stays on the admin page and does nothing.
Tried this in Firefox then Safari (mac), and happened on both, then on a new tab in safari it seemed to have logged me in, but when I click on any thing (modules, pages etc) it just takes me back to the log in screen.
This is an admin account, so not very useful if I can't get in

Any ideas?