What kind of install do you try to run? CD/DVD or perhaps FTP?
If it's FTP, the most probable reason is that SuSE can't connect to the specified FTP-server or the server is responding to slow.
I've had the same problem once. Switched to another FTP-server and all problems faded.
You can find a list of mirrors here
Hope this helps. If not, perhaps you can specify more information about your method and setup.