Following the attempted installation of a new setup, the installation crashed out as I had not set up the shortcuts correctly. There is no Remove label on the partial software system now on the target computer and it cannot be removed. The old application does not reside in the Registry. I've changed all the variables in a new setup but the installation procedure refuses to overwrite what is already there. I've no idea how it recoginzes the old system. So far have wasted 20 CDs and a whole day. Using Express 2009 and not disapppointed - it is still the most complicated and hard-to-use (782 pages of manuals 3" thick when printed out) piece of software imaginable.
Depending on how often you do this, it might be worth investing in some form of virtual machine software on which to test your installs, so you can just revert when temporary failures block further testing.
If you're just trying to save some time on a test machine (that is if you haven't already released this), it should be possible to just change your Product Code and optionally your Upgrade Code. You can do this under Organize Your Setup > General Information, category Product Properties. Also make sure you haven't set a Package Code, and that Generate Package Code is set to Yes (both on Prepare for Release > Releases, in the Express node). Then rebuild, and your next test should know very little about the previous.
(There are still potentially some interactions at the file level that the above won't change, but hopefully they will not cause difficulties. The most likely difficulty after a change like this is files getting left behind at uninstall due to SharedDLL counts. If they do cause problems, look into resetting your test environment.)
