The "T" on my 5150 is going crazy

​ Every now and then my T goes nuts- it starts typing over and over. It tends to do it more when I hit backspace or the down arrow, but sometimes it just types it for no reason, and when I quit whatever program I'm in, it goes back to normal. It does it in wordperfect as well as when I type email or am surfing online. I have Windows XP and wordperfect 11, if it makes a difference. Does anyone know if it's possible I unknowingly set some combination of keys on my computer to type the "T", like an accidental function key? ​