I'm just wondering if the setting for the task bar has changed. I'm thinking that perhaps - if you normally have the task bar hidden and only showing when you take your cursor to the lower edge of the screen, you will have your window(s) sitting lower on the screen. It sounds like the task bar is now always showing, meaning you can't get to the bottom of the window.
Maybe try checking the settings - take cursor to bottom of screen to show the task bar, right click on task bar, click Properties, put tick in AutoHide Task Bar, click Apply, OK.
If that hasn't solved it, then hopefully someone will come along with a better idea.