William Bartholomew posted a trick to the [ausDotNet] mailing list this arvo about when you need to know what is going on with an MSI installer, specifically the kind that come wrapped in a .exe bootstrapper.  It was in response to troubles Dr. Pete was having with the (acquired) Microsoft Office Groove 2007 Beta client...

See if you can extract the MSI packagr from the installer, usually OG-EN.exe /x c:\temp\

Then, you can use msiexec /i c:\temp\msifilename.msi /v* c:\temp\install.log

Then, open up install.log and see what it's complaining about.