Autoadminlogon is set to 0 when rebooting

To use Registry Editor to turn on automatic logon, follow these steps:

1. Click Start, and then click Run.
2. In the Open box, type Regedt32.exe, and then press Enter.
3. Locate the following subkey in the registry: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
4. Double-click the DefaultUserName entry, type your user name, and then click OK.
5. Double-click the DefaultPassword entry, type your password, and then click OK.

If you open regedit.exe and browse to HKLM:\Software\Microsoft\Windows NT\Current Version\Winlogon which is where you will also be storing the autologon username / password / domain, you should check for a DWORD called AutoLogonCount.... If this is set to 0, then on next reboot it will strip the password and set the AutoAdminLogon value back to 0. If you up the number, or simply delete the DWORD, all should come back to life as you'd expect.