Most basement windows installed during the initial construction of the home are commonly single pane glass windows. As the home ages, these windows may become difficult to open and close. Looking at the difference between basement windows and the other windows throughout the home, you notice that the basement windows are exposed to much more moisture which in turn may cause the steel or wood frame to rust or rot.
Some windows are not designed with energy efficiency in mind. As they age, moisture and humidity begin entering your home through the window. This is what causes that musty smell in the basement.
Water also can find a way in through the windows. In some cases, when there is no drain or the drain in the window well is clogged, water will accumulate in the window well increasing the pressure against the window and cause the window to break.