hi had a client with a Sony Vaio with similar problem she said it was dropped as high as her knee and suddenly some keys stopped working and other key where pressed simultaneously ex. 3 and f3. Plugged in an external keyboard and all work fine, opened the laptop and nothing out of place. So pretty easy dilemma : -undo all the keys clean all the contacts and retry it after a few hours of work or -replace with a new keyboard at the cost of 39.99 + labour. guess what i did