>Are you incrementing the version number in the COM DLL? I would think that that's crucial in order for the installer to detect the changes?
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>Another option: Skip the Interop assembly and go with dynamic typing in .NET 4.0. This removes the interop assembly and provides direct access (w/o strong typing however) for the COM DLL. One additional benefit is that dynamic will work with nested FoxPro types where Interop assembly imports will only give you top level properties and returned nested objects as 'object'.
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Yes, I was incrementing the version in the COM DLL. However, the interop DLL would remain at version 1.0.0.0. Since we're using a VS setup project to create the MSI, what I've decided to do was add a post-build event to hack the MSI itself and record a higher version number for the interop, which effectively forces the installer to copy the file down. This solution seems to do the trick.