Clive,
My apologies on that article, I must have read everything in there _except_ the fact that it wasn't supported for Windows XP. Must have been the idea that it was about Office XP that threw me off...
Anyway, to answer your question, yes, there is an MSI debugger that you can use to try and narrow down the problem. From the AdminStudio wrapper program, bring up the help and search for Debugging under the Index, that should give you a place to start.
Again, my apologies for the mixup, let us know if you have any other questions.