I can't log on any more why

I can not Log on like I use to

The standard way I use to log on to windows XP is to click on the

OK button on the window XP welcome screen that already had my user

name type in and no password needed to log in just click on the OK

button and my window desktop screen open up to run my computer.

The last thing I did before this problem started was I disable my

firewall and system security to download the updated Cox Security

Suite Powered by McAfee and the download was successful. So I

started with a full scan on the computer and check the little box

to log off when the scan is finish.

When I came back to Log on Like I usually do, I click the OK button to open up to my desktop screen. But now a little window pop up saying a logon
message your account has been disable please see your system
administor.

So I call Cox-Tech solution, over the phone they said do this and that, which I did and that did not fix the problem so they said over the phone that it a McAfee problem and I should call them, so they try to help me, but could not. So they said I needed to call microsoft. I call them, we try this and that and they could fix the problem so they said that I needed to contact my administrator, who I purchase my computer from.

So I call Dell and talk to a technician, He said he can help fix the problem but he needed some information on what I think started the problem.Like I mention above.

So now when I try to Log on a new window come up saying this

computer system #42D0051-595B is protected by a password

authentication system you cannot access this data on this computer

without the correct password, than it ask you to type in a primary

or administrate password and click enter.

If some one can help me fix this problem I will be thankful again.
I have a Dell Labtop Inspiron/9100 with window XP

Professional1-2cpu.

thank you
itallaboutHim