Hello, I integrated ACPICA into a real time operatinng system called "RTOS32". The "InitializeFullAcpi(void)" function runs without a problem. If I call function AcpiEnterSleepStatePrep(5) to prepare a system switch off I get the error messages: ACPI Error: [\_SB_.PCIO.LPCB.TPM_.PTS_] Namespace lookup failure, AE_NOT_FOUND(20130823/psargs-465) ACPI Error: Method parse/execution failed [\PTS] (Node 7F01B470), AE_NOT_FOUND(20130823/psargs-625) Is this a BIOS problem or did I something wrong with the ACPICA? BTW, AcpiEnterSleepStatePrep(5) returns with "AE_OK" which it shouldn't, IMHO. If I execute AcpiEnterSleepState(5) thereafter (because AcpiEnterSleepStatePrep did not returns an error) the ACPICA code crashes with a "privileged Instruction" exception. Which is probably not a surprise because AcpiEnterSleepStatePrep() already encountered a problem. Regards, Uwe P.S.: I'm a ACPI newbie so please excuse if I contacted the wrong forum.