After installing ASP.NET 2.0 on a box that hosts MCMS 2001 with Site Builder Refresh Site Builder Refresh will no longer work.
To resolve this problem it is necessary to create a NRClient.exe.config file inside the C:\Program Files\Microsoft Content Management Server\Client directory with the following content:
<?xml version =”1.0″?>
<configuration>
<startup>
<requiredRuntime version=”v1.1.4322″/>
<supportedRuntime version=”v1.1.4322″/>
</startup>
</configuration>
This is officially documented in the following KB article: https://support.microsoft.com?id=916132