Upgraded to v14.1 B741 and still does the same thing.
I will try your method again Scott as I did it before on old version and didn't help.
*UPDATE*
Nope didn't work. Even after a reboot.
Going to uninstall Opera.
I use 5 different browsers to make sure my site shows up online with all of them.
Gotta get this bug fixed before I roll out my updated site design..
Thanks.

When you go to Start > Default Programs > Associate a File Type....
Which browser is listed for html files?

Problem fixed.
I uninstalled Opera with Revo Unistaller as it will (and did) find many remnants left over from using the windows unistaller.
Then reinstalled Opera making sure that it wasn't set as default browser, as I did before, but didn't work.
And POOF!
CoffeeCup HTML is working normal again.
Time for bed now.
HAPPY NEW YEAR to everyone also from Saskatoon, SK, Canada.
**edit**
I should also mention that I did system restores before I did every step in case something didn't work.

-paintbrush-
html association was internet explorer, but didn't matter.

Glad you got it working – however it happened

We are in a new era. The Tools > Preferences > Browser Testing lists at the top of that tab
Preview
Internal Preview Uses: "Internet Explorer 11"
The drop-down menu offers only EARLIER versions of IE. <- THIS is where I want Chrome!

When I am coding my .htm file and use F11 to preview it, clicking on a URL opens a new window that announces that Internet Explorer is no longer supported.

That means F11 preview is no longer valid except for files in my working folder. To get a preview that references the internet, I need to drop down the top-border option "Test in Browser" and choose Chrome. That is a clumsy DELAY.