I just read at TechPowerUp that many OLPC XO notebook users are complaining about stuck keys:
Many participants in the program are now encountering what has come to be known as the 'stuck key' problem, in which one or more of the keys on their XO-1 laptop's built-in keyboard become stuck in an activated position, or are activated when adjacent keys are pressed. As of January 30th, the official word from OLPC is that the root cause of this problem is unknown because "there are several manufacturers of the keyboards". It is also unknown just how widespread this problem currently is, as the 30-day manufacturer's warranty has already expired for most G1G1 participants. However, the OLPC forums are full of reports. OLPC is currently deploying the XO-1 to children in Mongolia and Peru, as well as other developing nations. Meanwhile, members of the forums are also reporting that by taking the keyboard out of the XO laptop and rubbing on the underlying sensor, you might fix the stuck key, but that's not a 100% solution.