If you have any such device on your keyboard, you can try moving it to see if it seems to be more sensitive in one direction (the direction in which you are seeing scrolling issues). Hardware wise, there are a few keyboards with a wheel, lever, knob, or joystick type control which can be set to scroll as one of their functions.
Safest just to open Word documents or something local that you can check the scrolling in. I would caution against using the Internet if you see that safe mode also disables any antivirus / antimalware protection you have installed. This would start your computer with most drivers disabled, so you can immediately eliminate or confirm this without going and uninstalling them individually.
For instance, you could reboot into Safe Mode by tapping F8 repeatedly while the computer is booting up, so you see the startup options menu and can choose Safe Mode (with networking, if you want to use the Internet, but see below for caution). I would look towards drivers that can impact scrolling, such as Logitech SetPoint, Microsoft Keyboard and mouse center, and also touchpad drivers which can have settings such as scrolling when your touch is against the far side of the pad.
