What should I do to fix error 0x80029C4A in Visual Studio?

it's a programming error, in a scenario that you're trying to cast an object.

try put some break points in visual studio while you running the codes for debugging. post that line of code that generated the error above.

The error occured in one of our test computer. On the development computer, it does not appear. What could possibly  caused this? I find it hard to determine.

you need to enhance your existing program so that it can capture the exception to a log file and from there you got more details on what's exactly the error is.

the exception will usually tell you which line causing the error with the error details

The error tells the COM types are known (from registry), but the corresponding files like DLLs, Ocx are not found. This might be an 64/32bit mix issue.

Qlemo How do I determine/fix the 64/32 bit mix?

Simple. Is Office 64 or 32bit? How about VS? Both have to match. And Office might be installed diffently on machines.

Qlemo Both are 32 bit. Does it have an effect on machines running 64 bit Office when installing the MSI?

Sorry for the late recognition. It has been a hellish month for me. Thanks for all the support these guys have given me. Please continue doing the great stuff.