error starting service on win2k platform

Hey,
I am trying to install the Postgreql 8.1.3 on the windows 2k platform. While
installing I am getting the following error :
"Your local 'Power Users' group contains 'Authenticated Users' ".  This
Error has been previously discussed in the mailing list. (
http://archives.postgresql.org/pgsql-bugs/2004-09/msg00218.php )

I could not find how to remove the "NT AUTHORITY\Authenticated Users" from
the "Power Users" local group.

Please help me with this error.

Thanks and Regards
Parang Saraf
4th yr Undergraduate Student
Department of Computer Science and Engineering
Indian Institute of Technology, Kharagpur, India