can't login to my mailchimp account

I had a mailchimp acount for the last few months. I use it only to save e-mail addresses of my clients for a future mailing list.

Everything worked fine until a few days ago when I tried to log in and couldn't.

The Login page keeps returning to the same page.

no error massage, just does not log in.

I am working on an I mac with OS X 10.5.8

working with chrome Version 21.0.1180.90 which can't be updated on this OS X (too old for it...)

I have tried to log in from Safari Version 5.0.6 (5533.22.3) - did not work

BUT - from firefox 4.0.1 it did work for some reason

I have tried to follow instructions from the mailchimp suppurt page -

deleting cookies and emptying cache but it did not help.

Any Ideas?

Thanks a Lot

Naama