Windows XP keep restarting

Check the Task Manager for any programs that may still be running in the backgroung during shut down.

Troubleshoot the APM settings that may be affecting the shutdown process,try disabling or adjusting the system standby settings

There is another answer here and if its the correct one it wont be easy to fix. If your mains voltage is fluctuating the computer will restart all by it self. I've seen cases where switching something on in another room will start an ATX powered computer. Remember that these are never powered down unless you remove the power lead as there is always power to the M'Board and it only requires a momentary switch to start the computer normally. In extreme cases some one switching on an airconditioner somewhere in the same street or suburb can start these computers. If this si the case the only real fix is to buy a UPS and fit it in line between the mains and computer. Other than getting your electrical supplier to rerwire the area this is the only solution. But if this is the case you will need to buy a UPS that will drive both the computer and monitor so the bigger the monitor the bigger the UPS is that you need.

Or maybe instead of a UPS you could try a surge protector if you don't already have one.

To resolve the problem, disable the "Automatically Restart" option by
following these steps:

1. Right-click My Computer icon on desktop and click Properties.
2. Click the Advanced tab.
3. Under "Startup & Recovery" options, click Settings.
4. Deselect the "Automatically Restart" option under System Failure.
5. Click OK and then click OK again.

If the "Automatically Restart" option is disabled or missing under System Failure, set the value of the "AutoReboot" key to zero.

CAUTION: A registry backup is essential. An incorrect registry entry may cause serious system problems or prevent thecomputer from starting. You will not be warned of anyincorrect registry entries. If the registry is not backed up, the only way to recover the system is to reinstall the operating system.

To back up the registry, follow these steps:

a. Click Start and select Run.
b. Type Regedit in the Open field and click OK.
c. Click "Registry" in the menu.
d. Click "Export Registry" from the drop-down menu.
e. Click the down arrow beside "Save In" and select Local Disk (C:).
f. Type Backup.reg in the File Name field.
g. Verify that the "All" radio button under the "Export Range" is selected.
h. Click Save.

To set the value of the "AutoReboot" key to zero:

1. Click Start, select Run, and type Regedit.
2. Click the plus (+) sign next to HKEY_LOCAL_MACHINE.
3. Click the plus (+) sign next to System.
4. Click the plus (+) sign next to CurrentControlSet.
5. Click the plus (+) sign next to Control.
6. Click CrashControl to highlight it.
7. In the right-window pane, locate the "AutoReboot" key.
8. Right-click the "AutoReboot" key and select Modify from the menu.
9. Change the value of the key from 1 to 0.
10. From File Menu, click Exit.

Regards

Vasanthraj.C

XP restarts while shutdown:
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q311806

Additional Links:
*************
XP Shutdown Troubleshooters
http://www.aumha.org/win5/a/shtdwnxp.htm
http://www.theeldergeek.com/shutdown_issues_in_xp.htm

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