When I select Start->Turn off computer->Standby the 'turn off computer' option window closes, and then nothing else happens. I can start new applications, and Windows acts like I never selected standby. If I have a TV program scheduled to record I get a window asking if I'm sure, there are programs scheduled to record - and the computer just keeps running after I select yes. (If a program is not scheduled then that task in not running/in memory - this problem happens even if I'm not watching TV and no TV scheduling task is running.) This problem happens regardless of whether Media Center is running.

Windows XP SP3 Media Center Edition, all current updates installed.