mouse doesn't scroll

I have windows 8 and lately my mouse won't scroll all the time. Some folders more than others. I didn't have this problem a couple of weeks ago. I have 3 different mouses, and it is the same with all 3. Like it will scroll on this forum just fine. When I go to pictures or documents, that is when it scrolls intermittently. I did go into the mouse wheel settings and made it scroll more line and then just went back to making it slower to see if that did anything, but it made no difference

Its only going to scroll the active window and sometimes only when the mouse is actually over that window. If some other window is active or your mouse is outside that window it may not scroll.

I don't quite understand what you are saying. Let's say I have my pictures on the screen - sometimes it will scroll down and other times it won't. It is intermittent.