I have the exact model with the same problem. Tried everything but to no avail. I bought mine at Makro but did not have the receipt; but they used my card to verify when it was bought (8 months ago). I have sinced changed it and have received a new one. I suggest you take it back to where you bought it and get it replaced, or if you have had it over a year they may be able to send it away to be repaired.
Hope this helps. 'Good luck'.
Dolly
May 2008