if you have .net 2.0 on your server and you want to install SQL 2000 Reporting services, the installation will show that ASP.NET 1.1 is not registered on your web server even if you run aspnet_regiis command for asp.net 1.1 on yor web server.
To resolve this problem :
1) Un Install asp.net 2.0 from your web server by running the command :
2) Register asp.net 1.1 :
3) Install your SQL 2000 Reporting Services.
4) install your asp.net 2.0 on your web server.
Hope this helps.