I have tried to install Diagram Studio the latest version, having an old version installed. The installer tells me, that an old version is installed and should be uninstalled. If I click on yes (uninstall) the installer hangs. If I click No, it tells me that it cannot install and aborts.. If I use Uninstall from Control panel, the Installer hangs also.
So it is not possible to install a new version with this installer. I used the Setup.exe with date from 12.10.2012 as well as the
same from 21.09.2012. I have tried it on all of my 3 developement machines under windows7.
Try to uninstall it manually, by
removing the packages from Delphi, deleting all existing files, and then
removing the registry key from HKCU\Software\tmssoftware\TMS Diagram Studio.
Thanks for this post, also helped me to solve Diagram Studio and Workflow installation issues.