I found an article from Microsoft that may answer your question, which I have quoted below. The link to the page ishttp://www.microsoft.com/windowsxp/using/helpandsupport/learnmore/tips/nostandby.mspx
Ifyour computer won't enter standby or hibernation, it may requireupdated drivers. Power management features, especially standby andhibernation, rely on device drivers that support power management inaddition to compatible hardware. Incompatible video drivers preventthese features from working. The built-in VGA driver, for example, is abare-bones driver that doesn't support power management.
If standby and hibernate don't work, install an updated driver for your display adapter.
Tip taken from Microsoft Windows XP Inside Out
by Ed Bott and Carl Siechert. Published by Microsoft Press.
First check HPs website for updated drivers for your machine. Look at your drivers from the device manager and note the version numbers, then compare that with the version on the website.
If they are not helpful, you could try to manually update the drivers by finding them in the device manger, right click on each ACPI device (ACPI Lid, ACPI button, etc...) and select update driver.
If no updated ACPI drivers are available, check the power settings in the control panel. Under the 'Advanced' tab, there are options about what you want to happen when you close the lid, and when you press the power button. (Mine both say 'stand by'.)
To sum it all up:
- Check the power settings in the Control Panel /Check if it works
- Update Video Drivers /Check if it works
3. Update Motherboard and ACPI Drivers /Check if it worksReply with the results, then rate my solution. :)