Use modificated bios (advanced menu unlock) about one year on my Sony vpc-z13. But week ago something strange happened. Then I make command in windows - turn off PC - it just reboot. I try CLEAN install Win7 (x86 and x64), win8 and winxp - same trouble. But I found something. I try to rewrite bios by InsydeFlash.exe and ask to turn off PC after flash - and it turn off PC correctly. After this - try "live usb Ubuntu" - it correctly turn off PC. So I think something wrong bios - part, which respond for "windows-bios" communication. If this trouble only in Windows, clean install must fix it, but It didn't help. If you need bios dump, or some RW-Everything report - just say, i subscribe on thread updates and answer ASAP.