Why would adding a reference to a DLL fail on one of two computers of the same operating system/configuration?

I have two computers that are both W7-64. I am attempting to prepare the second computer (PC) to execute an IronPython automation suite that was built on the first computer (Master).

Currently, PC is failing when scripts reach the following line:

clr.AddReferenceToFileAndPath(Path.GetFullPath(r"C:\analyst_test\bin\Debug\Win32API.dll"))

Output:

SystemError:  The module was expected to contain an assembly manifest.(Exception from HRESULT: 0x80131018)

None of the files have changed, and the dll has not been changed in any way. Does Master require a manifest? Is Master finding a Manifest elsewhere? How can I resolve or work around this issue?

As Simon said, check that both machines have the same .NET version. Also, another common culprit is the VC++ redistributable version. If you set up fuslogvw it should give you more information.