Computer mouse is behaving mousey today

[pax americana]

My mouse has been behaving strangely today.

Whether it is Microsoft Windows OS or Linux OS, when I click and hold down the left mouse button to select text and release it, the highlighted text disappears. It means that I have to re-select it. I may need to repeat it a few more times before I can select the text for copying and pasting onto another part of my document.

I do not think the USB port into which my mouse is plugged is at fault because the latter exhibits the exact same behavior on my wife's notebook computer.

What is happening?

Is my desktop computer infected by a yet-to-be-discovered virus?

Is my mouse due for a replacement?

 

[michalrz]

Your left clickety clicker is looking to buy a farm.
It's possible to temporarily fix it, but it's not very professional and it could make things worse depending on the current state.

Just grab the mouse firmly with your southpaw and simply keep rapidly and quite firmly tap the mouse button for about 20 seconds to clean the microswitch.

 

[Nenu]

This^
I've kept a number of mice alive a bit longer using that method.
The writing is on the wall, mortgage the house cos you need a new mouse!

 

[cageymaru]

This^
I've kept a number of mice alive a bit longer using that method.
The writing is on the wall, mortgage the house cos you need a new mouse!

Now we need a budget from the OP so we can recommend him a replacement.