can't resize windows horizontally

I am working with windows 7 64 bit on an HP HDX. I have always been able to place my mouse pointer on the edge of my windows page and get a double sided arrow. Then I could hold down the mouse key and be able to drag the window to a smaller size and then if I released the button the window would stay at that size. Now if I put my mouse arrow on the side nothing happens. Only if I use the restore up or down box in the upper right corner will it work but if I try to open a new window it will go back to full size. Also if I place my mouse arrow on the menu bar and try to drag that window it automatically snaps to the restore down position. Have I done something to cause this and can I get it back to where it was before? Thank you.