Dell D620 fan doesn't work

Hi,

I have a problem with a Dell Latitude D620 laptop. The fan doesn't work. I tried the fan another laptop and it was working in that. I read some forum that the bios update fix the problem so I downloaded the latest BIOS version, the A10 version. I runned the update, but it didn't help. During the firmware update the fan started to work but the end the fan stopped. The update was successful although the problem has not fixed.
When I enter in the BIOS and in the Thermal Control Panel I turn off the "Bios thermal controls" and I can start the fan with the fan PWM option. But if I restart the laptop the fan wouldn't work again. How can I fix this problem?
Sorry for my english.

Thanks the help,

spgabor