Problems with selecting multiple lines of text

I usually click and drag straight downwards to select paragraphs or multiple lines of text in my browser or word.

Now I can only select a few lines before the text gets unselected and then it starts selecting text farther down where mty cursor is. Or if I drag too fast, the entire selection gets unselected. I also noticed that when I double click on a word or sentence, the whole word or sentence gets selected. If I drag veeery slowly downwards from left to right, I can manage to select a little more text than I would have if I did it at the normal speed.

I know there should be a way to fix this.

Some people have said there is no way to disable this in windows 7, but then, they're telling me that there is no way to select multiple lines of text which seems extremely inconvient.

Thanks!

Could be a flaky mouse button not holding its contact reliably. Try another mouse?

Replacing the mouse did the trick! Thanks for thinking of this simple solution!

Glad that did it :)