Possible reasons why the ASUS UX21E series cannot restore the system are as follows:

1. Expansion Memory failure: If the data is stored in the wrong memory address, it will cause the data to be unable to return to the correct operating state after being stored.

2. Incompatible external peripheral devices: For example, some external USB storage devices, memory cards (Compact Flash, MMC, Smart Media...) and other disk structures have special disk structures, which can easily cause them to enter standby (or hibernation) mode. Unable to cut off power or restore.

　3. Inappropriate drivers or applications: Inappropriate drivers can cause .dll, .sys and .exe files to refuse to enter standby or hibernation mode. In addition, for example, if an application suitable for Win 98 is installed in Win XP, since the application does not comply with the power management characteristics of the operating system, it is easy to cause recovery failure.

4. Operating system management failure: The current power management mode of Microsoft operating system is ACPI mode (Advanced Configuration and Power Interface), and its power configuration is managed by the operating system. If there is a problem with the operating system, it will naturally Will affect how the power supply configuration operates.