trick to quickly finding the error in a verbose MSI log
First, make sure you’ve got a verbose log (see Frequently Asked Questions About Windows Installer).
Second, open the log and search for “Return Value 3”.
Third, assuming you’ve found Return Value 3, look at the immediately preceding lines (previous 10 or so) in the log for the error.
Forth, have a look at the MSI SDK for context on the error: Windows Installer Error Messages [Windows Installer].