I had the same problem this past weekend. I couldn't get in using IE6, it would take me back to the login prompt. Using Netscape 4.72 I would get a system not available message. I noticed on Monday that I had accidently blocked all cookies from AMEX. I removed the block and got in immediately.
[This message has been edited by phoenixitc (edited 02-04-2003).]
[This message has been edited by phoenixitc (edited 02-04-2003).]