Mouse keeps auto scroll / flips tabs in start menu or tabs in web browsers

I am observing strange behavior with my mouse - where ever I point it, it appears to be sending scrolling signal to the underlying application. For example if I point it to the tabs in my web-browser then it auto flips to the next tab. If I point it to the start-menu button (launcher) then it flips through - Favourites → Leave → History → Computer → Application → Favourites… If I am trying to select an item from drop-down menu then its impossible with this mouse. I have to use the keyboard.

It is annoying to suffer this malfunction, but worse is that I dont know how I created it or how to fix it. Any clues or leads would be helpful and greatly appreciated.

I see that when using “konqueror” as browser. I also see it with “falkon”. I do not see it with “firefox”.

When using more than the one tab with “konsole”, I also see that behavior.

I’ve been assuming that this behavior is a feature, not a bug.