Try to calibrate the touch screen if it feels inaccurate. To calibrate the touch screen, tap the Menu icon and select Settings > Phone > Touch settings > Screen calibration, and follow the instructions on the screen.
If it does not help. reset factory settings. Backup your phone before doing so.
If it does not help, try to update with the latest available sw for your phone.
If it does not help, visit the Nokia Care Point in your area. For contact information, go to your local Nokia support page.