I found others were having the same issue with .net on win2000 this was the answer i found in google

had that problem and the following fixed it: 1)share inetpub/wwwroot on all drives as inetpub/wwwroot$. 2)Make at least 60MB free space on all drives on pc. 3)Install as default install-do not change default install options.4)Make sure the local Administrator has full permissions to the share
5. Make sure you are logged on as an administrator and re-run setup.
6)Uninstall visual studio 6 analyzer if u have it.
7.Ensure the home directory of the default web site on iis is the same as the install directory for .net.

try it HTH