I have contacted the developper of synaptic driver, and for sure it's 
the fault of SCI interrupt handler.
I can reproduce it because I never lose sync when I don't access to 
/proc/.../temperature and when I access it, exactly at the same time, I 
lose the sync.

Yu, Luming wrote:

>It sound like serious one, if SCI interrupt handler was blamed for this issue.     --Luming
>
>-----Original Message-----
>From: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org [mailto:acpi-devel-admin@lists.sourceforge.net]On Behalf Of Pavel Machek
>Sent: 2003?12?2? 2:28
>To: roychris
>Cc: acpi-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
>Subject: Re: [ACPI] SCI interrupt handler : spend too much time
>
>
>Hi!
>
>  
>
>>Since 2.6, when I read /proc/acpi/thermal/THR*/temperature and battery
>>info, my system spends too much time in SCI interrupt handler and it
>>loses the sync of my mouse, a synaptic. Any issue ?
>>    
>>
>
>Can you repeat it? Losing sync of mouse is probably a bug in inputs,
>and should be fixed.
>								Pavel
>  
>