"Restart Now" button in Support Assistant doesn't work so I can't check for or install updates

[Leo3791]

I noticed that I hadn't received any updates for a while, so I started HP Support Assistant, clicked on "Updates" and got a modal pop-up saying that I need to restart my computer ("A restart is required to complete updates. Shutting down alone will not implement updates. Some HP Support Assistant features cannot be accessed until updates are completed") - and offering me the option to "Restart Later" or "Restart Now".

The Restart Now button doesn't do anything though - I've tried manually restarting the machine and uninstalling and reinstalling Support Assistant, but I still get that pop up (with the non-working "Restart Now" button) when I try to check for updates.

Any idea how to fix that?

[Venom21]

Use Revo Uninstaller (free version) to uninstall HP Support Assistant. After installation, select it from the list, choose "Advanced" scan mode, and click "Scan." It will detect leftover files, folders, and registry entries, click "Select All," then "Delete" to remove them. Repeat until clean, then restart your PC, reinstall HP Support Assistant from HP's site, and test updates.