problems in administrative rights

After automatic updates were allowed on my computer running WindowsXp with
SP2 I have found that there is a new user account created under user accounts
in control panel as "ASP.NET Machine.A..." with password protection and
limited account. the oproblem that I seenm to be facing is that My
adminstrator rights appear to be taken away from me as when I right click on
any folder and click "Properties" it no more shows anything and same is the
case with the option of "sharing and Security".
When I coonect to internet however these features are again restoed
momentarily after some time but as soon as I restart the same problem
resurfaces
I have microsoft.NET framework 1.1 installed and also Norton Internet
Security 2005. Please help me. It's very Urgent.