I installed V12.1 on 4 machines without issue. Machine #5 will not go into the dialog to allow me to install as a client will start to install the databases and services. I've uninstalled a few times and started over with no help. I've deleted the install directory and checked for residual data in %appdata%. I also checked the registry and while I did see some entries for zfirm I did not see anything that looked like it would cause this.