Macbook Air fan goes crazy

Scenario:

Out of nowhere, the fan of my Macbook Air goes crazy from time to time. Even I have been doing nothing but looking at the blank desktop wallpaper! Huge fan noise and the upper left corner of the Air (near the power inlet) becomes really hot.

Configuration:

2011 MacBook Air with 1.7GHz Intel Core i5, 4GB RAM and Mac OS X 10.8.2

Cause:

Checking at the activities in the machine, I found this process (displayed by the top command):

USER             PID  %CPU %MEM      VSZ    RSS   TT  STAT STARTED      TIME COMMAND

khtsoi           501  98.8  1.6  2606200  67320   ??  Rs    4:07PM   0:05.10 com.apple.quicklook.satellite

After searching the "Quicklook" and "Satellite" keywords in the Internet, some one suggested that the cause is Quicklook tries to call QuickTime to generate thumbnails for video files which are not supported by the QuickTime codec.

Then I realised that this process re-spawns itself every time when I click on the "Downloads" folder icon in the Dock. The default action of this click is to expand the folder contents in grid mode. Even I did not have any video/audio files in that folder, I noticed that the thumbnail of a M$ Word file is not rendered. All files after this Word file are also displayed as an empty box without the thumbnail image.

So, I fired up the "Activity Monitor" tool from the "Utilities" folder, select on the "QuickLookSatellite-general" process and click the "Inspect" icon from the tool bar. Under the "Open Files and Ports" tab, I confirm that the last thing this process trying to read is that M$ Word file.

Solution:

Everything is fine after removing the Word file from the "Downloads" folder. I can open that file with the M$ Word correctly and that file is 13MB. There are other M$ Word files in the same folder but they have never caused similar problem.

Edit: one more step to really get rid of the noise (in software level).

Problem:

The fan still goes crazy and the Air is still hot even the quick lock.satellite is gone. There is no heavy duty process showing up in top or the "Activity Monitor". But I notice there are something wrong in the system log. I found the following three errors message keep showing up in the system log (by going to "Applications" -> "Utilities" -> "Console" and select the "All Messages".)

mdworker[1626]: Unable to talk to lsboxd

sandboxd[1633]: ([1631]) mdworker(1631) deny mach-lookup com.apple.ls.boxd

kernel[0]: Sandbox: sandboxd(1627) deny mach-lookup com.apple.coresymbolicationd

Cause:

I don't know and I don't care. It's better to leave it to Apple to explain it to its customers.

Solution:

Step 1: Modify the system configure file (you need to be root to do so). Edit the /System/Library/Sandbox/Profiles/system.sb file to append the following three lines at the end:

;;; FixSandboxErrors

(allow mach-lookup (global-name "com.apple.ls.boxd"))

(allow mach-lookup (local-name "com.apple.ls.boxd"))

Step 2: Clear the cache (you need to be root to do so) by running the following command.

rm -fr /System/Library/Caches/*

Step 3: Safeboot the Mac.

 - Shutdown the Mac first (remember to enable speaker volume before shutdown).

 - Start up the Mac. Just after the startup tone (cannot do it before the tone), press and hold the shift key.

 - When the grey apply logo appears, release the shift key.

 - After the system is up to the login screen, confirm that there is a red "safeboot" label at the upper right screen corner.

 - Then you can simply restart the Mac.

Enjoy the Mac without the fan noise.