Question for groups using PAHT

It looks like we've gotten TPAHTS fully and successfully installed now, at least in our sandbox and test environments.  However, while the sandbox installation was (mostly) straightforward, the test installation was really difficult, finally requiring a lot of (invaluable) help from Tessitura support.

What remains a mystery is how the two environments wound up being so different.  The issue boiled down to the fact that while ASP.NET 3.5 was installed on both systems, the installation itself was somehow radically different.  In our development environment it was installed in the manner and with the libraries that Tessitura expected:  namely in C:\Program Files\Microsoft.NET\, and with the file C:\Program Files\Microsoft.NET\Primary Interop Assemblies\adodb.dll, which was the source of our errors.  In our test environment (which mirrors our live environment) ASP.NET is installed in C:\WINDOWS\Microsoft.NET, and lacked a "Primary Interop Assemblies" directory.

We're not sure how the installations would wind up so different.  Presumably these frameworks were installed using the same Windows Update procedure.  We observed that one commonality between the servers being referenced at Tessitura and our dev environment was that they had SQL Server installed on them, while our test and live web servers do not, but do not have anything beyond that.

Our solution to get this running was to create the folder path expected by the "working" .Net installs, containing only the referenced DLL, which we then registered using the appropriate command line tool.

Has anyone else run across this issue, or understand why .NET installations might be so different?