Small but annoying problem with clickable links

[#1]

Using Firefox and Thunderbird.
Up till last week, clicking a link on an email opened the (closed) browser AND then opened the link.
Now the first click simply opens the (closed) browser. I have to click the link a 2nd time for the web page to open.
I had a recent encounter with some crummy software - FISSA, which kept installing itself as my home page when I simply use blank:blank.
Got rid of that, which I think has caused this 2nd problem. Any solutions welcome

[#2]

Try using CCleaner ... and then use the Registry Cleaner on the left panel of CCleaner,  to see if it shifts "whatever it is" ,...

[#3]

Thanks for the recommendation.....unfortunately....although Ccleaner removed a pile of stuff, the problem persists even after a reboot.
I'm stuck with this, I suppose, as a "feature" for next 12 months when I am upgrading.
Unless somebody can suggest anything else.

[#4]

Try "Malwarebytes".... and "Eusing Registry Cleaner"....
Eusing Registry Cleaner usually finds stuff that CCleaner leaves behind !...
(Both FREEEEEE !..so no cost to you !)

[#5]

Nope - that don't find anything either.
Seems to me that a simple change to the registry is needed somewhere - but where?

[#6]

Have a look at http://support.microsoft.com/kb/175775
You may have to reset everything and have Internet Explorer as the default web browser, then when things are fixed you will be able to change that back to Firefox.