ps I am using IS Express 2008. I have deduced bu using Orca I can delete various rows concerning _IsMaintenance but editing the MSI is not a viable solution for me... ... View more

I ran into the same issue; I needed to try and prevent IS installing over an existing installation since the user is free to type in whatever path they want in the Destination Folder dialog. Like me you don't so much want to know if it is already installed, rather, where. What i ended up doing was calling out to a Custom Action .exe that I wrote , After Destination Folder Dialog. THis exe just scans the folder chosen for some well known files and if it finds any then i assume the user has picked an old installation folder. Then i throw up a mesagebox to warn them (which you must force on-top BTW). I set IS to ignore the return code and wait for the action to complete. All you can do is warn the user and tell them to press 'Back' in the wizard that follows. If you tell IS to take note of the return code you will see an annoying error message. And that means I had to then introduce a superfluous "Ready to Install" dialog into the wizard to allow a BAck action. This is a really fundamental thing - IS Express has obviously been cut back severely to get you to buy Premier or Professional. It's really just for shareware installations i reckon, no good for serious business apps. Hope that helps, Andy ... View more