My laptop's fan often works fine when the laptop isn't heated. But when i indulge it in some heavy activity and when it starts to get heat up. The fan stops automatically even though when the fan stops the laptop isn't heated that much. When the fan stops the laptop shutdown due to over heating. And when i instantly restart it the laptop fan never starts from the boot up not until the laptop cools down .but often it won't start until i leave it for a hour. Whenever the fan works fine there shall come a point when the fan would stop working. sometime the period extends to half hour and some time even 3 hours if I'm just browsing and stuff. I took it to repair shop and got the fan cleaned and serviced but the problem sustains. The person told me it has sensor whenever it shuts down the fan the fan would resume start spinning when necessary. Sometimes this happens but most of the time it doesn't. The fan is absolutely fine, i got it tested. I think it has something to do with the sensor or built in settings. I cannot afford another laptop. I need a simple software or settings solution. Maybe a way i could restart the fan whenever it stops. And yeah the fan varies in speed according to laptop need but as i told it would stop after some point. Help!!!!!