Keyboards on Windows computers can repeat letters when key press sensitivity is too high. This problem can be rectified by adjusting your keyboard's repeat frequency. Once this is lowered, key presses will occur slower and you will not have the letters repeated instantly.
Click"Start," then "Control Panel."
Click "Hardware and Sound," followed by "Keyboard."
Move the "Repeat delay" slider further to the left below the "Character repeat" option. The further left the slider moves, the longer the delay will be before a character repeats.