There are a couple of differences between 4.1 and 4.2 that make it absolutely necessary that 4.1 is completely uninstalled and all its relevant folders are deleted before 4.2 is installed in order to avoid conflicts. In case you want to transfer your current show from 4.1 to 4.2 follow these steps:(if you just want to upgrade to 4.2 and start a clean show ignore step 1)
1) Export the components you want to keep the settings/maps/warps for.
2) Open Task Manager (right-click on taskbar)->Services tab, right-click and stop the FanControllerService and the LEDManagerService.
3) Uninstall 4.1 (right click on Start button->Programs & Features, double-click on Hippotizer Version 4.1.0 and follow the uninstall wizard).
4) Delete both folders C:\HippotizerV4 and C:\HippoTools
5) Make sure that the machine is connected to the Internet before you reboot your machine and run the 4.2 installer and follow the installation wizard. This may require a reboot and you must reboot when prompted. The installation should continue automatically after the reboot.