Acer Laptop overheating with ACPI error that I don't understand.

I am having overheating problems with my Acer Aspire laptop.
# uname -a
FreeBSD ed.local.net.mx 8.0-BETA1 FreeBSD 8.0-BETA1 #256: Thu Jul  9  
07:05:20 CDT 2009      
root_at_ed.local.net.mx:/usr/obj/usr/src/sys/ENCONTACTO  i386

I've been having this problem for several months and compensating by  
reducing dev.cpu.0.freq from 1900 to 1200 and 800 in warm offices.

The errors I'm seeing in the log files are:

+acpi_ec0: EcRead: failed waiting to get data
+ACPI Exception: AE_NO_HARDWARE_RESPONSE, Returned by Handler for  
[EmbeddedControl] 20090521 evregion-531
+ACPI Error (psparse-0633): Method parse/execution failed  
[\\_TZ_.THRM._TMP] (Node 0xc4e75960), AE_NO_HARDWARE_RESPONSE

I'm afraid that I don't understand them.

Any suggestions appreciated,

ed