Belong to Computers | Hardware or Software | Operating system.
In Windows' controll pannel, sellect "Mouse".
Sellect the "Weel" tab.
It's probably set to scroll by page (seccond option) or, maybe, by some large number of lines, like something around 60 to 100... (if the first option is sellected).
Sellect the first option and set the number of lines to a reasonable value like 2, 3 or 4.
Click "OK".
Now, it should behave correctly.
If you have problem using the scroll bar on the side: Instead of dragging with the mouse, you may try using the up and down arrows of your keyboard. Each tap will scroll one line up or down. Hold the key to scroll faster. It's often beter than dragging for very large or long documents.
Use the "Page UP" and "Page Down" keys to jump a full page.
Electro
January 2014