WinXP Home: error"login w/ Admin Privs"

I am the administrator of my home office computer, but selected programs have abitrarily come up with the following error, "please logon with Administrator privileges and try again" These programs are either recently installed or reinstalled, usually gaming software, but I am the primary user and have full admin privileges as per the XP Home logon options. Unfortunately, the Home OS doesn't have the shares and grps assignment functionality of Pro, so I am stuck. I feel that the answer may be inRegedit or MMC, but my skills are novice at best in those areas, so I need specific How-Tos where they are concerned. Thanks.
-Frederick McLeish