I've the same problem with an asus notebook.
System: Host: asus Kernel: 3.2-0.towo.3-siduction-amd64 x86_64 (64 bit, gcc: 4.6.2)
Desktop KDE 4.7.2 (Qt 4.7.4) Distro: siduction 11.1-rc One Step Beyond - kde-lite - (201112212148)
Machine: System: ASUSTeK product: F3T version: 1.0 serial: NB-1234567890
Mobo: ASUSTeK model: F3T version: 1.00 serial: NB-0123456789
Bios: American Megatrends version: F3TAS.229 date: 11/07/2008
CPU: Dual core AMD Turion 64 X2 Mobile TL-60 (-MCP-) cache: 1024 KB flags: (lm nx sse sse2 sse3 svm) bmips: 8036.72
Clock Speeds: 1: 2009.184 MHz 2: 2009.184 MHz
Graphics: Card: nVidia G73 [GeForce Go 7600] bus-ID: 04:00.0
X.org: 1.11.3.901 drivers: nouveau (unloaded: vesa,fbdev) tty size: 179x37 Advanced Data: N/A for root
Network: Card-1: Atheros AR242x / AR542x Wireless Network Adapter (PCI-Express) driver: ath5k bus-ID: 01:00.0
IF: wlan0 state: up mac: 00:15:af:26:a8:ba
Card-2: nVidia MCP51 Ethernet Controller driver: forcedeth port: bc00 bus-ID: 00:14.0
IF: eth0 state: down mac: 00:1a:92:cf:29:2a
Drives: HDD Total Size: 160.0GB (50.5% used) 1: ST9160821AS
Info: Processes: 197 Uptime: 1:10 Memory: 1158.5/2008.4MB Runlevel: 5 Gcc sys: 4.6.2 Client: Shell inxi: 1.7.27
I leave the system with shut down on KDE, the system goes down and stops with
" Will now halt"
"[SOME NUMBERS] Power down"
The system stay in the console and switches not off.
I have to press the powerbutton for about 5 seconds, then is the system off.
Shutdown -n-P now from the console fails too.
I've tried in the grub menue "acpi=off"
The result is the same in letters like above "" and if i press then the powerbutten, the system switches immediately off.
I started siduction.iso from a usb-stick, the result is, the system switches not off. I tried aptosid2011_02.iso, the same result as describt before. aptosid2011_01.iso switches the system down and off. A test with a sidux.iso is also good.
Since i have this problem, switch off, there is another one with the battery energy display. This means the battery is corrupt.
After this tests, my meaning is some moduls in the kernel do not cooperate.
If some logs requiered, please let me now, i will try to post it.
Thanks
sepps