I tried to apply this fix: http://linuxmint.com/forum/viewtopic.php?f=90&t=21283&p=125219&hilit=cycle+hard#p125219
but it seems that the power management is completly broken. When the power manager doesn't detect properly the powerstate, acpi triggers (closing the lid, idle time etc etc) don't make the laptop suspends/hibernates or park the HD's heads and so on. However, it seems that the screensaver works (at least, a dark screen despite of the power manager is set to "suspend the screen after x minutes", maybe it's a normal behaviour I don't know) and the screen switches off a few minutes later...
Obviously, the laptop mode is set to true.
I have no idea how to fix it.