Have tried to upgrade Garmin Express on Win 8.1, 64-bit desktop, Win 10, 64-bit laptop, Win 7, 32-bit laptop. File downloaded directly from Garmin. Success on both laptops, but continual fail on 8.1 desktop, even when running as administrator or trying compatibility wizard. Previously had Express 6.18 on PC but cannot upgrade to 6.20. Mistakenly uninstalled 6.18 thinking it might present the problem, but now cannot find legacy Express software to re-install 6.18. Suggestions?