404 error in Apache 2.0.49 ...

My Apache service has started and appears to be running
fine, and I've had an IP address allocated to me by my ISP
(let's call it "1.2.3.4") pointed to a web server name (say,
" www.domain.com") ...

Trouble is, although the content of the site shows up when
accessed through its constituent files (by entering, for example,
"C:\Program Files\Apache Group\apache2\htdocs\index.html"),
I get a "404 File Not Found" error trying to access the
server by any other means (such as addressing it as "www.
domain.com", "1.2.3.4" or "127.0.0.1")

I know my 'net connection is working fine, because websites
other than mine appear to be working correctly, and restarting
the server doesn't cause anything to be reported in the
Event Viewer.

So, what does this "404" error normally indicate is wrong,
how I can find out the name of the file that can't be found
what can be done to fix the problem in my case?

Thanks,
Russell

me too.. how do you fix this error ?? Can you share me please ?