Strange ACPI Behaviour (ACPI: Unable to turn cooling device [df80df18] 'on')

PC: Compaq SR1265CL, Gutsy (7.10)

---------------------------------------------------------------------------------------------
root@compaq:~# uname -a
Linux compaq 2.6.22-14-generic #1 SMP Sun Oct 14 23:05:12 GMT 2007 i686 GNU/Linux

root@compaq:~# cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 6
model : 10
model name : AMD Athlon(tm) XP 3200+
stepping : 0
cpu MHz : 2200.082
cache size : 512 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse syscall mmxext 3dnowext 3dnow up ts
bogomips : 4405.24
clflush size : 32

root@compaq:~# cat /proc/acpi/thermal_zone/THRM/trip_points
critical (S5): 100 C
passive: -248 C: tc1=4 tc2=3 tsp=60 devices=CPU0
active[0]: -266 C: devices= FAN

root@compaq:~# cat /proc/acpi/thermal_zone/THRM/temperature
temperature: 65 C

root@compaq:~# tail -n 10 /var/log/messages
Nov 16 04:09:37 compaq kernel: [14840.912268] ACPI: Unable to turn cooling device [df80df18] 'on'
Nov 16 04:09:43 compaq kernel: [14846.906282] ACPI: Unable to turn cooling device [df80df18] 'on'
Nov 16 04:09:49 compaq kernel: [14852.900369] ACPI: Unable to turn cooling device [df80df18] 'on'
Nov 16 04:09:55 compaq kernel: [14858.894347] ACPI: Unable to turn cooling device [df80df18] 'on'
Nov 16 04:10:01 compaq kernel: [14864.888352] ACPI: Unable to turn cooling device [df80df18] 'on'
Nov 16 04:10:07 compaq kernel: [14870.882397] ACPI: Unable to turn cooling device [df80df18] 'on'
Nov 16 04:10:13 compaq kernel: [14876.876460] ACPI: Unable to turn cooling device [df80df18] 'on'
Nov 16 04:10:19 compaq kernel: [14882.870423] ACPI: Unable to turn cooling device [df80df18] 'on'
Nov 16 04:10:25 compaq kernel: [14888.864437] ACPI: Unable to turn cooling device [df80df18] 'on'
Nov 16 04:10:31 compaq kernel: [14894.858534] ACPI: Unable to turn cooling device [df80df18] 'on'

---------------------------------------------------------------------------------------------

In Feisty, I could change the trip points as described here: http://ubuntuforums.org/showthread.php?p=3610514

Now, I can't. I get an error:
root@compaq:~# echo -n "65:60:50:55:50:45" > /proc/acpi/thermal_zone/THRM/trip_points
bash: echo: write error: Invalid argument
65:60:50:55:50:45

Any ideas? Thanks!!