My computer sometimes won't standby or hibernate

[Guest]

I love XP's feature to autostandby or autohibernate. However, sometimes I
notice that it mysteriously does not happen - even if I there are no active
network connections of any sort.

Does anyone know how to debug this? The Event Viewer shows nothing. The
only symptom is that I can come back a while later and the computer has not
standbied or hybernated.

 

[Guest]

I should add that if I enter standby or hibernate manually, it works fine.

 

[Ted Zieglar]

Power saving modes were intended for laptops; they can be balky when used
with a desktop.

"The Computer Cannot Enter Standby or Hibernate If a Direct3D-Based Screen
Saver Is Running"
http://support.microsoft.com/default.aspx?scid=kb;en-us;306676

"Unable to Use Power Management Features"
http://support.microsoft.com/default.aspx?scid=kb;en-us;302414

 

[Guest]

Sorry for not being more clear:

A) It is a laptop (Compaq Presario R3000)
B) It can hibernate and standby manually fine - but it no longer does it
automatically
C) I am not running any special screen saver, playing any games, etc.