Unfortunately I can't give you the debugging procedure to do that.
What would need to happen here is that you would have to make sure to let Sun know that there is a problem you are seeing with their install and they would have to contact our support department.
After that we would take the appropriate steps.
Don't know if this will help or not.... I too had this "interface not registered" problem and searched everywhere and tried everything. Nothing would work for me. So I reinstalled Windows (2000) and I still had the problem. Then I flashed my BIOS with the latest version - and evething was ok.
I think a previous BIOS update somehow interfered with InstallShield.... Or hey it could be completely unrelated (I was trying a lot of things to get it fixed). Might be worth a try though!