Windows 7 has a new feature called Aero Snap. Snap is a quick way to resize open windows, by dragging them to the edges of your screen. Depending on the edge (top, bottom, left or right), the window will maximize, normalize or position side by side with another window. If you do not like this feature then you can disable this. Here is how :
- Open Control Panel in Windows 7.
- In the Control Panel, navigate to Ease of Access Center → Change how your mouse works
- Scroll down in the options list. Place a checkmark in the checkbox labeled Prevent windows from being automatically arranged when moved to the edge of the screen.
- Click OK to save the settings.