Autologon

I have set on my safe PC (WXP Home edition) the Autologon
funtion with the help of TweakUI (I use a Name and NO
Password). This appears to function only ONE time. When I
have started up my PC the setting is reset. By which
program ? I think it is the MS AntiSpy BETA. I have
another PC also with WXP Home, same procedure, WITHOUT MS
Antispy BETA and there is no problem at all with this
Autologon setting. Well, in my first mentioned PC, I have
deactivated two System Agent Checks: "Windows Password
Protection" and "Windows Logon Policies". No success.
What am to do to let it function as I want ?
Greetings JanA.