WordPress MU

I've just installed WordPress and all I've done so far is change the header from within Options. I closed down the computer for the night, and now (next morning) find I am unable to log into Admin via IE. After quite a while of trying to load the Admin page, I get an IE notification saying "the page cannot be displayed".

I tried in Firefox, and after a couple of failures, was able to get into the Admin, but when I tried changing the header again in Options, I got a notification that: "404 Not Found
The requested URL was not found on this server."

I've enabled cookies, cleared them and the cache etc, but no joy from that.

Does anyone have any clues as to what could be going wrong, please?

Check the error logs, pls. They are on the server - go in thru cpanel or whatever.

This sounds like a server side issue. If you do not have access to your logs, or if access is limited (as in a shared hosting environment), then you may have to send a ticket to your hosting provider to see if they were running maintenence on any of the servers that contains your account.

Not much of a help I know, but I hope it gets you started in the right direction.

It almost sounds as if it is a temporary problem and it may clear itself up without any notice.