I got my laptop back today.
They actually gave me a new 2G stick of free ram since the one installed was not from HP.
It got me a little worried, because it could have been a memory problem only.
Back home, I changed the hard drive to the one with Linux on it and after some checks, I am sure the board is a "new" one (refurbished) never really knew what that means.
The mac address has changed and the GPU is running at a higher temperature.
Let's hope that it will last a couple of years.