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) You may also need to manually remove the mongodb database and files. Check your services in Computer management and make sure the MongoDB service has been removed (is not listed) and then delete the folder C:\ProgramData\GreenHippo\MongoDB. To manually remove the MongoDB service, run a command prompt as Admin and then type SC delete MongoDB and press enter. You should get a confirmation message from the Services manager of Success.
6) Reboot your machine, 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.
These steps must be taken any time you are installing software from 4.2 onward on a machine that has 4.1 or earlier already installed. An example of this is if you factory restore a machine that originally had 4.1 installed on it and you are installing the latest release of software.