Hi 'La Tua'. Sounds like your "webby" is faulty. You say it's built into the laptop. Is your machine still under warranty from the supplier or manufacturer? If it is, go back to supplier and tell them you want it either fixed or totally replaced.
If it is outside the warranty, have you got a local engineer you know or someone who'll look at it? Replacing the built-in webcam is a major operation, especially if you're not "into" computers. I would have a look at it - for free - but I'm too far away!!
Seein it works now and again it is probably the connection to the laptop's motherboard that's faulty. You could try opening the laptop and trying to see but I dont advise it unless you know what you're doing.
That's about it. Let me know how you get on.