jcd,
Error 1606 usually indicates that either a necessary key is missing from the registry or that something in the registry points to a file or directory that does not exist.
Make sure that the HKEY_LOCAL_MACHINE\Software\Microsoft\VisualStudio\6.0\Setup registry key contains a value named VsCommonDir that contains the path to the Common directory under your Visual Studio install directory.
TonyH
Measurement Studio