Win XP system won't go into standby mode by itself

I don't think I misunderstood your problem.  The setting in the Power Control panel sets the system to go into Standby after so many minutes of inactivity.  So now we need to know what "inactivity" means.  According to Jose (and I agree), any background program or task that wakes up and uses more than a certain amount of CPU will reset the internal time-out value for going into Standby.  This means that a program such as a Virus protection program may wake up and decide to scan your hard drive.  This will make your computer look busy, and hence the time left before going into Standby gets set back to Maximum again.

To debug this problem, you need to shut down processes that are running until you find the one that is keeping your system alive.  One way to do this is to use "msconfig" to limit what runs at startup on your computer.

"How to troubleshoot configuration errors by using the System Configuration utility in Windows XP"

  < http://support.microsoft.com/kb/310560 >

HTH,

  JW

Java Quick Starter causes the problem.

On my computer, a Toshiba laptop, standby and/or hibernation would not automatically run. By trial and error I figured out that the Java Quick Starter (jqs.exe), if it is running, causes standby and hibernation not to work.

To fix this go to Control Panel >   Java  > Advanced > Miscellaneous. Uncheck Java Quick Starter.

Problem fixed.

In addition to what Wunders says, let me add that if there is any process on your system that uses 10% or more CPU even for a split second, your Stand By/Hibernate timer will get reset back to zero and start over again.

For example, if you have programs like these installed:

Windows Search, Skype, iTunes, MagicJack, RSS feeds, any kind of Instant Messenger, any kind of malware scanners doing scans or doing automatic updates like MSE, AVG, Avast, Norton, McAfee, Bit Defender...  they can prevent your system from entering Stand By/Hibernation.

Describe your current antivirus and anti malware situation:  McAfee, Norton, Spybot, AVG, Avira!, MSE, Defender, ZoneAlarm, PC Tools, Comodo, etc.

Any one of these can prevent your system from entering Stand By/Hibernate if they are "doing their thing" when your Stand By/Hibernate time comes around.  If they are checking the Internet for something to do, looking for updates, scanning, indexing, etc.

Therefore, it is possible that your system may never Stand By/Hibernate as the timer keeps getting reset every time some process uses 10% or more of the CPU.

If you have the timer set to one hour and something happens that uses 10% of the CPU every 30 minutes, you will never automatically Stand By/Hibernate.  Both will still work just fine manually though.  Just because your system looks "idle" or you think it is idle, XP may not think so.

If you take a look at Task Manager, it could show 99% idle, but you would have to watch it for a while and maybe see something that uses 10% - even for a split second if you are lucky enough to see it.

You should test the Stand By/Hibernation mechanism itslef to be sure there is nothing wrong with it by setting the time down to something small - like 1 minute for a test.  If it works okay then and not when you set it to one hour, you know something is running that is resetting your timer so you must figure out what it is and then decide what to do about it or reduce the time to something smaller - 15 minutes, 30 minutes, etc. until you find the time that works the best for your system and the things you have installed.

Stand By is inherently dangerous anyway and I will never use it.  I would always use Hibernate instead.  If you Stand By, you will still have information and perhaps open files and things in RAM.  If the system were to lose power in Stand By, you might lose that information or end up with corrupted files.  Hibernate removes the possibility of that happening.