Touchscreen not responding properly

Hi,

I have just replaced the front glass on a samsung galaxy s2 i9100 I brought. The touchscreen on the bottom doesn't seem to respond properly I can't press anything on the bottom 1cm or so of the screen. The odd thing is I can use the bottom to swipe the screen left and right and also when I write a message the bottom of the screen works fine I can press it with no problems and it responds so I can't understand why it doesn't work else where. Now and again the phone freezes and I need to lock the phone then unlock it for it to respond again and if I plug the charger even less of the screen responds. Any help would be appreciated