I am only musing here but I do not think many sites are built with a fixed size over 800 pixels wide. Those that show full width on a larger screen (as this site does) are set up to fill the screen they are being displayed on. The hit counter on one of my web sites shows that about 80% of the traffic are using a resolution of 800 x 600, most of the rest are 1024 x 768 with a tiny few larger. Based on that I wonder if your problem might be due to a setting on your computer rather than the sites you view. Give us a link to a site that requires you to scroll sideways.

Start. Control Panel. Mouse. Choose the Buttons tab. For "Scroller", set to the following: Check the box labeled "Use MS Office compatible scroll only." Also, check the box labeled "Scroll in active window only."

Chris, in control panel when i right click the mouse icon it gives a set up window, I hit the "buttons" tab and assign the functions I want to the buttons. I can get to the controls ok but there is no place to set the middle wheel except to scroll any # of lines. LX 3 optical mouse not cordless

Have you tried rebooting? Check for Windows Updates too. Another keyboard shortcut is to use the backspace key to go back, shift+backspace will go forward. Are you sure there's a page to go back to? If a link opened in a new window or tab, you won't be able to back up. Click the button to the right of the Forward button and it'll give you the recent pages history. You can also use that to select the page you want. Only other thought off the top of my head is, have you noticed a bunch of dog treats being delivered lately? Maybe Harry and Sam have been...