Dell Vostro 3500 loses/lost WiFi-connection / drops out of WLAN and does not re-connect because of overheating

After being on for a few hours, my wifes' laptop lost WiFi Connection and direfused to reconnect. Leaving it off for some time then, WiFi was working fine again.

How-I-fixed.-it:
Monitoring the problem for a few days I recognized that the downside of the laptop was very warm at the time it lost WLAN connection. I remembered having troube with this system in the past due to overheating because of a dusty fan assembly, as described in a previous post: http://how-i-fixed-it.blogspot.de/2013/05/laptop-dell-vostro-3500-turns-itself.html

I disassembled the system and found the heat exchanger filled with dust. I cleaned the whole fan assembly and since the system is much cooler now, also the WiFi is stable.

Laptop Dell Vostro 3500 turns itself off without prior notification because of system becoming too warm

One day my wife's Dell Vostro 3500 Laptops started to turn itself off when in use without any warning message or notification. Turning it on again it worked for a while an then powered off again without any hint where the problem may be caused by.

How-i-fixed-it:
I turned out to be caused by the fan assembly air outlet being full of dust so that no air was going through it any more to cool down the system. To get to it to clean it means disassembling the whole system but following the procedure well described in the service Manual under "
Removing the Heat Sink and Fan Assembly",
it took me about an hour to get the job done and since that, the system is running fine again.

Here's the link to the Dell Vostro 3500 Service Manual:
ftp://ftp.dell.com/Manuals/all-products/esuprt_laptop/esuprt_vostro_notebook/vostro-3500_service%20manual_en-us.pdf

Update: Had to clean it again Apr. 2014, Mai 2015.
Seems like it need yearly maintenance :-)
 Here are some images how the fan assembly looked like: