Keyboard ghost

Hello,
When I am on the internet and there is a search field. If I click in there, the computer just starts writing 6666666666666666666666666 all on its own. I have a heck of a time trying to type stuff, I have to hold down the backspace and then continue to type until it stops. Sometimes it does it and it just goes on forever or if I happen to need a 6 in my words, then it just goes by itself, or it doesn't work at all. I thought maybe it was dirty under the key so I removed it and cleaned under it and it still does it with both the 6 above the T and the 6 on the number keypad.