why can i not access http://ABC1 but can access http://ABC1/SUSadmin ?

Webserver? Apache?

It looks as if the defaiult directory (htdocs) has no index.html page, or whatever is set is not accessible (what Operating system are you using?), and thete is no .htaccess file.

sebserver (iis)
i am using windows 2000 server
thanks

If SUSadmin is a subweb of ABC1 then the permissions are most likely different. In IIS ensure you have the security settings correct and that you have the correct default document set. Under documents check the files listed and make sure you have the same file available in your website.

Go to the inetpub directory and check the NTFS permissions on the wwwroot folder and make sure you have permission to access the folder. The SUSadmin should be a subdirectory under wwwroot and more than likely has unique permissions set on it.

RCMB

If you do not have directory browsing enabled then you need a default document in the directory your accessing.

"if i type http://ABC1/SUSadmin i get the SUS administration page but if i type in http://ABC1 i get the message that "you are not authorized to view this page". the page http://ABC1/SUSadmin is on our intranet so i thought that by typing http://ABC1 i could browse this directory. "

Have a look at your access control file (typical name access.conf or .htaccess file under the dir).

they might has soemthing like:

 <Location /SUSadmin/>
    order deny,allow
    deny from all
    allow from xxx.xxx.
  </Location>

  The above setting will only allow machine in the IP range of xxx.xxx to access to "SUSadmin"