How do I debug the failure to register a dll as part of an mbuild?

Setup:

• Windows 8
• MATLAB R2010a 32-bit
• MATLAB Builder EX
• Microsoft Visual Studio 2008
• Running as administrator

I have a project created that is using MATLAB Builder EX to created a dll for use in Excel. The build seems to progress ok, until it tries to register the dll.

I get the following error:

--> mwregsvr C:\Temp\myTest.dll
(LoadLibrary)Error: 0x000000c1 Message: %1 is not a valid Win32 application.
C:\SOFTWARE\MATHWO~1\32_BIT~1\BIN\MEX.PL: Error: regsvr32 for C:\Temp\myTest.dll failed.

All of my intermediate files get destroyed (probably due to the build process ending in an error).

Some things that I would check if I knew how:

• Verify that the 32-bit version of RegSrver32 is being called to register the dll
• Keep the intermediate files around and try to register it manually

What else could I try/look at?

I have successfully built this same project on another machine, but I cannot figure out the differences.