Help: View Timing Report can't find web browser

[kinithin]

If I click on View Timing Report (from the Develop menu), I get the error

'Viewing Timing Report' requires a web browser, such as Firefox, Chrome, Safari, or Internet Explorer. No web browser could be located - is your browser set up properly?

I get a similar error message for View Unused Resources.

Both Firefox and Chrome are installed, and there's nothing special about how I installed them. They work perfectly fine otherwise, including when I choose Manage License... (from the License menu) and Hero Lab Manual (from the Help menu).

Any ideas?

Win 10 Pro. Firefox 58.0.2 (64-bit) [default browser]. Chrome 64.0.3282.167 (Official Build) (64-bit).