Try this code:

#DEFINE EWX_LOGOFF        0 
#DEFINE EWX_SHUTDOWN      1 
#DEFINE EWX_REBOOT        2 
#DEFINE EWX_FORCE         4 
#DEFINE EWX_POWEROFF      8 
#DEFINE EWX_FORCEIFHUNG  16 

DECLARE INTEGER ExitWindowsEx IN user32; 
    INTEGER uFlags, INTEGER dwReserved 

* logoff -- change user 
* = ExitWindowsEx (EWX_LOGOFF, 0) 

* reboot 
= ExitWindowsEx (EWX_REBOOT, 0)

For Windows NT try this code:

DECLARE INTEGER GetLastError IN kernel32 

DECLARE SHORT InitiateSystemShutdown IN advapi32; 
    STRING  lpMachineName,; 
    STRING  lpMessage,; 
    INTEGER dwTimeout,; 
    SHORT   bForceAppsClosed,; 
    SHORT   bRebootAfterShutdown 

IF InitiateSystemShutdown ("", "User time is out", 10, 0, 1) <> 1 
* Common reasons for failure include an invalid 
* or inaccessible computer name or insufficient privilege. 

    *   5 = ERROR_ACCESS_DENIED 
    * 120 = ERROR_CALL_NOT_IMPLEMENTED -- not supported in Win9* 
    ? "Error code:", GetLastError() 
ENDIF

There is another API function allowing to restart Windows:

    DECLARE INTEGER RestartDialog IN shell32; 
        INTEGER hParent, STRING pszPrompt, LONG dwFlags 

If you want to suspend or hibernate your system, here is an API function for this too:

DECLARE INTEGER SetSuspendState IN Powrprof; 
    INTEGER Hibernate, INTEGER ForceCritical,;
    INTEGER DisableWakeEvent