Ok, I'll be clearer, on the machine that works is VS2008 installed, on the machine that doesn't work (i.e. uses VS2005) I have both VS2008 and VS2005. So your statement:
"Prior to VBP v6.7, the Make VS.NET / 2005 / 2008 actions used the latest version of MSBuild.exe that was found. With VBP 6.7 and later, they use the version that matches the project or solution file being built (2.0 for VS 2005, 3.5 for VS 2008) if available."
doesn't help me because it is obviously not finding the "latest version of MSBuild.exe".
I still need to know "How does VB6 Pro 6.2a determine which VS version to use?", i.e. which macros/environment variables does it use to find VS?
James