First thing: probably some little filthy parts inside the mouse (dirt) blocking the wheel, open it and clean it
Some programs are opened and run in the background when you start up your computer. Even programs who aren't in your autostart folder. Try this: while normally being in windows, press: CTRL + ALT + DELETE
You'll get a menu with all the menus that are currently opened. When you see one, simply double click on the name and it will close. Repeat that ( first CTRL+ALT+DELETE again and then double click on name in list) wthl all the names of every program and it will save you up loads of free RAM memory, making your computer go faster