In the failing job, use the "Additional command line options" box to enter "/le C:\Logs\InstallError.txt" (the path being whatever you like). That should tell you what the real issue is with the 1603. Failing that, change the "/le" to "/lv" and search for 1603 in the resulting file. Read up from there. You should see something more useful like folders that don't exist. CustomActions failing because of user state, or something. There are MANY things that can cause a 1603, but it's usually a pretty standard ICE error that causes it... and these are generally the "Directory", "CustomAction", "InstallExecuteSequence" type issues. Running it through ORCA (from Microsoft) may give you a hint as well.