Administrative rights Compromised

Hi,
i have windowsxp with Sp2,Microsoft.net framework1.1 & Norton Internet
Security2005. After allowing automatic updates Ihave run into afew problems
reccently. they are:-


1.) I have got this ASP.NET Machine A... account from somewhere in control
panel.
2.) I am logged onto as Administrator but I have lost my Administrative
rights it appears as:- a.) On right clicking on any file or foldert and
clicking properties nothing happens,i.e. properties not shown. Same with
alt+Double click.

However after connecting to internet the problem 2.) was solved but when I
restarted my computer the problem resurfaced and now again when i 'm
connected to internet it seems to have gone away although automatic
installation of updates is not turned on now.

Please suggest what to do

Reply A.S.A.P
Bye

I don't see any mention of antivirus or spyware/malware scan.

I would
chkdsk /f the drive
scan for spyware/malware AFTER I updated
scan for virus's AFTER I updated
run regclean [download off the internet]