RivaTuner is an overclocking and hardware monitoring system for Windows devices that is used to enhance GPU performance. At this point, it is outdated, with the last stable version being released in 2009.
We have found that if you have RivaTuner installed on your device, Proton VPN will not open.
To use Proton VPN, you must uninstall RivaTuner and download either RivaTuner Statistics Server or MSI Afterburner. These are more current programs, and they support the latest graphic cards.